feat: Replace per-preview Caddy sidecars with shared gateway architecture

Refactor preview deployments to use a single shared Caddy gateway container
with subdomain routing (<previewId>.localhost:<port>) instead of one Caddy
sidecar and one port per preview. Adds dev/preview modes, git worktree
support for branch checkouts, and auto-start on phase:pending_review.

- Add GatewayManager for shared Caddy lifecycle + Caddyfile generation
- Add git worktree helpers for preview mode branch checkouts
- Add dev mode: volume-mount + dev server image instead of build
- Remove per-preview Caddy sidecar and port publishing
- Use shared cw-preview-net Docker network with container name DNS
- Auto-start previews when phase enters pending_review
- Delete unused PreviewPanel.tsx
- Update all tests (40 pass), docs, events, CLI, tRPC, frontend

apps/server/cli/index.ts

@@ -1353,8 +1353,9 @@ export function createCli(serverHandler?: (port?: number) => Promise<void>): Com
           phaseId: options.phase,
         });
         console.log(`Preview started: ${preview.id}`);
-        console.log(`  URL: http://localhost:${preview.port}`);
+        console.log(`  URL: ${preview.url}`);
         console.log(`  Branch: ${preview.branch}`);
+        console.log(`  Mode: ${preview.mode}`);
         console.log(`  Status: ${preview.status}`);
         console.log(`  Services: ${preview.services.map(s => `${s.name} (${s.state})`).join(', ')}`);
       } catch (error) {
@@ -1394,7 +1395,7 @@ export function createCli(serverHandler?: (port?: number) => Promise<void>): Com
           return;
         }
         for (const p of previews) {
-          console.log(`${p.id}  http://localhost:${p.port}  ${p.branch}  [${p.status.toUpperCase()}]`);
+          console.log(`${p.id}  ${p.url}  ${p.branch}  ${p.mode}  [${p.status.toUpperCase()}]`);
         }
       } catch (error) {
         console.error('Failed to list previews:', (error as Error).message);
@@ -1415,8 +1416,9 @@ export function createCli(serverHandler?: (port?: number) => Promise<void>): Com
           return;
         }
         console.log(`Preview: ${preview.id}`);
-        console.log(`  URL: http://localhost:${preview.port}`);
+        console.log(`  URL: ${preview.url}`);
         console.log(`  Branch: ${preview.branch}`);
+        console.log(`  Mode: ${preview.mode}`);
         console.log(`  Status: ${preview.status}`);
         console.log(`  Initiative: ${preview.initiativeId}`);
         console.log(`  Project: ${preview.projectId}`);