feat(16-04): add TanStack Router file-based routes and app shell layout

Create route structure with __root, index (redirect to /initiatives),
initiatives/index (dashboard stub), initiatives/$id (detail stub with
type-safe params), and inbox (stub). Add AppLayout with persistent nav
header matching wireframe: title, New Initiative button, navigation tabs
with active highlighting. Disabled tabs for Agents/Tasks/Settings (out
of scope). Replace temporary health-check App with RouterProvider.
Route tree auto-generated by TanStack Router Vite plugin.

packages/web/src/App.tsx

@@ -1,16 +1,8 @@
-import { trpc } from './lib/trpc';
+import { RouterProvider } from '@tanstack/react-router'
+import { router } from './router'
 
 function App() {
-  const health = trpc.health.useQuery();
-
-  return (
-    <div className="p-8">
-      <h1 className="text-2xl font-bold">Codewalk District</h1>
-      <p className="text-muted-foreground mt-2">
-        Server: {health.data?.status ?? 'connecting...'}
-      </p>
-    </div>
-  );
+  return <RouterProvider router={router} />
 }
 
-export default App;
+export default App

packages/web/src/layouts/AppLayout.tsx

@@ -0,0 +1,57 @@
+import { Link } from '@tanstack/react-router'
+import { Button } from '@/components/ui/button'
+
+const navItems = [
+  { label: 'Initiatives', to: '/initiatives', enabled: true },
+  { label: 'Inbox', to: '/inbox', enabled: true },
+  { label: 'Agents', to: '#', enabled: false },
+  { label: 'Tasks', to: '#', enabled: false },
+  { label: 'Settings', to: '#', enabled: false },
+] as const
+
+export function AppLayout({ children }: { children: React.ReactNode }) {
+  return (
+    <div className="min-h-screen bg-background">
+      {/* Header */}
+      <header className="sticky top-0 z-50 border-b bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60">
+        <div className="mx-auto flex h-14 max-w-7xl items-center justify-between px-6">
+          <Link to="/initiatives" className="text-lg font-bold tracking-tight">
+            Codewalk District
+          </Link>
+          <Button size="sm" onClick={() => { /* placeholder - Phase 17 */ }}>
+            + New Initiative
+          </Button>
+        </div>
+        {/* Navigation */}
+        <nav className="mx-auto flex max-w-7xl gap-1 px-6 pb-2">
+          {navItems.map((item) =>
+            item.enabled ? (
+              <Link
+                key={item.label}
+                to={item.to}
+                className="rounded-md px-3 py-1.5 text-sm font-medium text-muted-foreground transition-colors hover:text-foreground"
+                activeProps={{
+                  className: 'rounded-md px-3 py-1.5 text-sm font-medium text-foreground bg-muted',
+                }}
+              >
+                {item.label}
+              </Link>
+            ) : (
+              <span
+                key={item.label}
+                className="cursor-not-allowed rounded-md px-3 py-1.5 text-sm font-medium text-muted-foreground/50"
+              >
+                {item.label}
+              </span>
+            )
+          )}
+        </nav>
+      </header>
+
+      {/* Page content */}
+      <main className="mx-auto max-w-7xl px-6 py-6">
+        {children}
+      </main>
+    </div>
+  )
+}

packages/web/src/routeTree.gen.ts

@@ -0,0 +1,113 @@
+/* eslint-disable */
+
+// @ts-nocheck
+
+// noinspection JSUnusedGlobalSymbols
+
+// This file was automatically generated by TanStack Router.
+// You should NOT make any changes in this file as it will be overwritten.
+// Additionally, you should also exclude this file from your linter and/or formatter to prevent it from being checked or modified.
+
+import { Route as rootRouteImport } from './routes/__root'
+import { Route as InboxRouteImport } from './routes/inbox'
+import { Route as IndexRouteImport } from './routes/index'
+import { Route as InitiativesIndexRouteImport } from './routes/initiatives/index'
+import { Route as InitiativesIdRouteImport } from './routes/initiatives/$id'
+
+const InboxRoute = InboxRouteImport.update({
+  id: '/inbox',
+  path: '/inbox',
+  getParentRoute: () => rootRouteImport,
+} as any)
+const IndexRoute = IndexRouteImport.update({
+  id: '/',
+  path: '/',
+  getParentRoute: () => rootRouteImport,
+} as any)
+const InitiativesIndexRoute = InitiativesIndexRouteImport.update({
+  id: '/initiatives/',
+  path: '/initiatives/',
+  getParentRoute: () => rootRouteImport,
+} as any)
+const InitiativesIdRoute = InitiativesIdRouteImport.update({
+  id: '/initiatives/$id',
+  path: '/initiatives/$id',
+  getParentRoute: () => rootRouteImport,
+} as any)
+
+export interface FileRoutesByFullPath {
+  '/': typeof IndexRoute
+  '/inbox': typeof InboxRoute
+  '/initiatives/$id': typeof InitiativesIdRoute
+  '/initiatives/': typeof InitiativesIndexRoute
+}
+export interface FileRoutesByTo {
+  '/': typeof IndexRoute
+  '/inbox': typeof InboxRoute
+  '/initiatives/$id': typeof InitiativesIdRoute
+  '/initiatives': typeof InitiativesIndexRoute
+}
+export interface FileRoutesById {
+  __root__: typeof rootRouteImport
+  '/': typeof IndexRoute
+  '/inbox': typeof InboxRoute
+  '/initiatives/$id': typeof InitiativesIdRoute
+  '/initiatives/': typeof InitiativesIndexRoute
+}
+export interface FileRouteTypes {
+  fileRoutesByFullPath: FileRoutesByFullPath
+  fullPaths: '/' | '/inbox' | '/initiatives/$id' | '/initiatives/'
+  fileRoutesByTo: FileRoutesByTo
+  to: '/' | '/inbox' | '/initiatives/$id' | '/initiatives'
+  id: '__root__' | '/' | '/inbox' | '/initiatives/$id' | '/initiatives/'
+  fileRoutesById: FileRoutesById
+}
+export interface RootRouteChildren {
+  IndexRoute: typeof IndexRoute
+  InboxRoute: typeof InboxRoute
+  InitiativesIdRoute: typeof InitiativesIdRoute
+  InitiativesIndexRoute: typeof InitiativesIndexRoute
+}
+
+declare module '@tanstack/react-router' {
+  interface FileRoutesByPath {
+    '/inbox': {
+      id: '/inbox'
+      path: '/inbox'
+      fullPath: '/inbox'
+      preLoaderRoute: typeof InboxRouteImport
+      parentRoute: typeof rootRouteImport
+    }
+    '/': {
+      id: '/'
+      path: '/'
+      fullPath: '/'
+      preLoaderRoute: typeof IndexRouteImport
+      parentRoute: typeof rootRouteImport
+    }
+    '/initiatives/': {
+      id: '/initiatives/'
+      path: '/initiatives'
+      fullPath: '/initiatives/'
+      preLoaderRoute: typeof InitiativesIndexRouteImport
+      parentRoute: typeof rootRouteImport
+    }
+    '/initiatives/$id': {
+      id: '/initiatives/$id'
+      path: '/initiatives/$id'
+      fullPath: '/initiatives/$id'
+      preLoaderRoute: typeof InitiativesIdRouteImport
+      parentRoute: typeof rootRouteImport
+    }
+  }
+}
+
+const rootRouteChildren: RootRouteChildren = {
+  IndexRoute: IndexRoute,
+  InboxRoute: InboxRoute,
+  InitiativesIdRoute: InitiativesIdRoute,
+  InitiativesIndexRoute: InitiativesIndexRoute,
+}
+export const routeTree = rootRouteImport
+  ._addFileChildren(rootRouteChildren)
+  ._addFileTypes<FileRouteTypes>()

packages/web/src/router.tsx

@@ -0,0 +1,10 @@
+import { createRouter } from '@tanstack/react-router'
+import { routeTree } from './routeTree.gen'
+
+export const router = createRouter({ routeTree })
+
+declare module '@tanstack/react-router' {
+  interface Register {
+    router: typeof router
+  }
+}

packages/web/src/routes/__root.tsx

@@ -0,0 +1,16 @@
+import { createRootRoute, Outlet } from '@tanstack/react-router'
+import { AppLayout } from '../layouts/AppLayout'
+
+export const Route = createRootRoute({
+  component: () => (
+    <AppLayout>
+      <Outlet />
+    </AppLayout>
+  ),
+  notFoundComponent: () => (
+    <div className="p-8 text-center">
+      <h1 className="text-2xl font-bold">Page not found</h1>
+      <p className="text-muted-foreground mt-2">The page you are looking for does not exist.</p>
+    </div>
+  ),
+})

packages/web/src/routes/inbox.tsx

@@ -0,0 +1,14 @@
+import { createFileRoute } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/inbox')({
+  component: InboxPage,
+})
+
+function InboxPage() {
+  return (
+    <div>
+      <h1 className="text-2xl font-bold">Agent Inbox</h1>
+      <p className="text-muted-foreground mt-1">Content coming in Phase 19</p>
+    </div>
+  )
+}

packages/web/src/routes/index.tsx

@@ -0,0 +1,7 @@
+import { createFileRoute, redirect } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/')({
+  beforeLoad: () => {
+    throw redirect({ to: '/initiatives' })
+  },
+})

packages/web/src/routes/initiatives/$id.tsx

@@ -0,0 +1,16 @@
+import { createFileRoute } from '@tanstack/react-router'
+
+export const Route = createFileRoute('/initiatives/$id')({
+  component: InitiativeDetailPage,
+})
+
+function InitiativeDetailPage() {
+  const { id } = Route.useParams()
+  return (
+    <div>
+      <h1 className="text-2xl font-bold">Initiative Detail</h1>
+      <p className="text-muted-foreground mt-2">Initiative ID: {id}</p>
+      <p className="text-muted-foreground mt-1">Content coming in Phase 18</p>
+    </div>
+  )
+}

packages/web/src/routes/initiatives/index.tsx

@@ -0,0 +1,19 @@
+import { createFileRoute } from '@tanstack/react-router'
+import { trpc } from '../../lib/trpc'
+
+export const Route = createFileRoute('/initiatives/')({
+  component: DashboardPage,
+})
+
+function DashboardPage() {
+  const health = trpc.health.useQuery()
+  return (
+    <div>
+      <h1 className="text-2xl font-bold">Initiative Dashboard</h1>
+      <p className="text-muted-foreground mt-2">
+        Server: {health.data?.status ?? 'connecting...'}
+      </p>
+      <p className="text-muted-foreground mt-1">Content coming in Phase 17</p>
+    </div>
+  )
+}