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/shared/SettingsDefaultsManager.ts

@@ -49,6 +49,8 @@ export interface SettingsDefaults {
   CLAUDE_MEM_CONTEXT_SHOW_LAST_MESSAGE: string;
   CLAUDE_MEM_CONTEXT_SHOW_TERMINAL_OUTPUT: string;
   CLAUDE_MEM_FOLDER_CLAUDEMD_ENABLED: string;
+  CLAUDE_MEM_TRANSCRIPTS_ENABLED: string;  // 'true' | 'false' - enable transcript watcher ingestion for Codex and other transcript-based clients
+  CLAUDE_MEM_TRANSCRIPTS_CONFIG_PATH: string;  // Path to transcript watcher config JSON
   // Process Management
   CLAUDE_MEM_MAX_CONCURRENT_AGENTS: string;  // Max concurrent Claude SDK agent subprocesses (default: 2)
   // Exclusion Settings
@@ -108,6 +110,8 @@ export class SettingsDefaultsManager {
     CLAUDE_MEM_CONTEXT_SHOW_LAST_MESSAGE: 'false',
     CLAUDE_MEM_CONTEXT_SHOW_TERMINAL_OUTPUT: 'true',
     CLAUDE_MEM_FOLDER_CLAUDEMD_ENABLED: 'false',
+    CLAUDE_MEM_TRANSCRIPTS_ENABLED: 'true',
+    CLAUDE_MEM_TRANSCRIPTS_CONFIG_PATH: join(homedir(), '.claude-mem', 'transcript-watch.json'),
     // Process Management
     CLAUDE_MEM_MAX_CONCURRENT_AGENTS: '2',  // Max concurrent Claude SDK agent subprocesses
     // Exclusion Settings