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>

CHANGELOG.md

@@ -0,0 +1,22 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## [0.1.0] - 2025-01-XX
+
+### Added
+- Initial open source release
+- BYO-key authentication (OpenAI, Anthropic)
+- Full 3-panel interface (Nodes | Focus | Chat)
+- Vector search with sqlite-vec
+- Integrate workflow for connection discovery
+- Content extraction (YouTube, PDF, web)
+- Easy/Hard mode toggle (GPT vs Claude)
+- MCP server for external AI assistants
+- Local SQLite database with embeddings
+
+### Notes
+- macOS only for v0.1.0 (Linux/Windows support coming)
+- Requires Node.js 18+ and native build tools for better-sqlite3