feat: isolate Claude and Codex session sources

Persist platform_source across session creation, transcript ingestion, API query paths, and viewer state so Claude and Codex data can coexist without bleeding into each other.

- add platform-source normalization helpers and persist platform_source in sdk_sessions via migration 24 with backfill and indexing
- thread platformSource through CLI hooks, transcript processing, context generation, pagination, search routes, SSE payloads, and session management
- expose source-aware project catalogs, viewer tabs, context preview selectors, and source badges for observations, prompts, and summaries
- start the transcript watcher from the worker for transcript-based clients and preserve platform source during Codex ingestion
- auto-start the worker from the MCP server for MCP-only clients and tighten stdio-driven cleanup during shutdown
- keep createSDKSession backward compatible with existing custom-title callers while allowing explicit platform source forwarding

src/cli/handlers/file-edit.ts

@@ -9,6 +9,7 @@ import type { EventHandler, NormalizedHookInput, HookResult } from '../types.js'
 import { ensureWorkerRunning, workerHttpRequest } from '../../shared/worker-utils.js';
 import { logger } from '../../utils/logger.js';
 import { HOOK_EXIT_CODES } from '../../shared/hook-constants.js';
+import { normalizePlatformSource } from '../../shared/platform-source.js';
 
 export const fileEditHandler: EventHandler = {
   async execute(input: NormalizedHookInput): Promise<HookResult> {
@@ -20,6 +21,7 @@ export const fileEditHandler: EventHandler = {
     }
 
     const { sessionId, cwd, filePath, edits } = input;
+    const platformSource = normalizePlatformSource(input.platform);
 
     if (!filePath) {
       throw new Error('fileEditHandler requires filePath');
@@ -42,6 +44,7 @@ export const fileEditHandler: EventHandler = {
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({
           contentSessionId: sessionId,
+          platformSource,
           tool_name: 'write_file',
           tool_input: { filePath, edits },
           tool_response: { success: true },