feat: add Omega Mac native macOS SwiftUI chat app

Native macOS counterpart to the web Omega agent, connecting directly
to the OpenAI API and TPMJS tool registry (1M+ AI-ready tools).

- SwiftUI app targeting macOS 15+ with dark theme
- Full agentic loop: auto-discover tools via BM25, stream OpenAI
  responses, execute tools via remote sandbox, loop up to 10x
- SwiftData persistence for conversations, messages, tool runs
- Keychain storage for API keys and environment variables
- SSE streaming via URLSession.bytes with custom parser
- Actor-based services (OpenAIService, TPMJSRegistryService)
- NavigationSplitView layout with sidebar + chat detail
- MarkdownUI for rendering assistant responses
- Settings: API key, model picker, env vars, custom system prompt
- Keyboard shortcuts: Cmd+N new chat, Cmd+, settings, Enter send

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pnpm-lock.yaml

@@ -1014,6 +1014,22 @@ importers:
         specifier: ^5.9.3
         version: 5.9.3
 
+  packages/tools/official/agentmail:
+    dependencies:
+      ai:
+        specifier: 6.0.49
+        version: 6.0.49(zod@4.3.5)
+    devDependencies:
+      '@tpmjs/tsconfig':
+        specifier: workspace:*
+        version: link:../../../config/tsconfig
+      tsup:
+        specifier: ^8.5.1
+        version: 8.5.1(jiti@2.6.1)(postcss@8.5.6)(tsx@4.21.0)(typescript@5.9.3)(yaml@2.8.2)
+      typescript:
+        specifier: ^5.9.3
+        version: 5.9.3
+
   packages/tools/official/anomaly-detect-mad:
     dependencies:
       ai: