fix: OS release prep - bootstrap script, deps, docs

- Fix bootstrap script (.env.example.local → .env.example)
- Fix @langchain/core version conflict (^1.0.1 → ^0.3.0)
- Add settings:open event listener for LocalKeyGate button
- Pin Next.js to 15.1.3 (was "latest")
- Default runtime to 'local' mode
- Remove desktop app references from UI text
- Rewrite MCP docs for web-only context
- Add SECURITY.md, CODE_OF_CONDUCT.md, CHANGELOG.md
- Add docs/README.md, docs/TROUBLESHOOTING.md
- Update README with platform support table

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tsconfig.json

@@ -33,5 +33,5 @@
     }
   },
   "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
-  "exclude": ["node_modules", "dist", ".next", "apps/mac/src-tauri/target", "backups"]
+  "exclude": ["node_modules", "dist", ".next", "backups", "vitest.config.ts"]
 }