feat: Add persistent chat sessions for iterative phase/task refinement

Introduces a chat loop where users send instructions to an agent that
applies changes (create/update/delete phases, tasks, pages) and stays
alive for follow-up messages. Includes schema + migration, repository
layer, chat prompt, file-io action field extension, output handler chat
mode, revert support for deletes, tRPC procedures, events, frontend
slide-over UI with inline changeset display and revert, and docs.

apps/server/container.ts

@@ -20,6 +20,7 @@ import {
   DrizzleChangeSetRepository,
   DrizzleLogChunkRepository,
   DrizzleConversationRepository,
+  DrizzleChatSessionRepository,
 } from './db/index.js';
 import type { InitiativeRepository } from './db/repositories/initiative-repository.js';
 import type { PhaseRepository } from './db/repositories/phase-repository.js';
@@ -32,6 +33,7 @@ import type { AccountRepository } from './db/repositories/account-repository.js'
 import type { ChangeSetRepository } from './db/repositories/change-set-repository.js';
 import type { LogChunkRepository } from './db/repositories/log-chunk-repository.js';
 import type { ConversationRepository } from './db/repositories/conversation-repository.js';
+import type { ChatSessionRepository } from './db/repositories/chat-session-repository.js';
 import type { EventBus } from './events/index.js';
 import { createEventBus } from './events/index.js';
 import { ProcessManager, ProcessRegistry } from './process/index.js';
@@ -56,7 +58,7 @@ import type { ServerContextDeps } from './server/index.js';
 // =============================================================================
 
 /**
- * All 11 repository ports.
+ * All 12 repository ports.
  */
 export interface Repositories {
   initiativeRepository: InitiativeRepository;
@@ -70,10 +72,11 @@ export interface Repositories {
   changeSetRepository: ChangeSetRepository;
   logChunkRepository: LogChunkRepository;
   conversationRepository: ConversationRepository;
+  chatSessionRepository: ChatSessionRepository;
 }
 
 /**
- * Create all 11 Drizzle repository adapters from a database instance.
+ * Create all 12 Drizzle repository adapters from a database instance.
  * Reusable by both the production server and the test harness.
  */
 export function createRepositories(db: DrizzleDatabase): Repositories {
@@ -89,6 +92,7 @@ export function createRepositories(db: DrizzleDatabase): Repositories {
     changeSetRepository: new DrizzleChangeSetRepository(db),
     logChunkRepository: new DrizzleLogChunkRepository(db),
     conversationRepository: new DrizzleConversationRepository(db),
+    chatSessionRepository: new DrizzleChatSessionRepository(db),
   };
 }
 
@@ -171,6 +175,8 @@ export async function createContainer(options?: ContainerOptions): Promise<Conta
     repos.pageRepository,
     repos.logChunkRepository,
     options?.debug ?? false,
+    undefined, // processManagerOverride
+    repos.chatSessionRepository,
   );
   log.info('agent manager created');