feat(vscode-bridge): Copilot Chat bridge (OpenAI facade + JSON-RPC tools)

- Implements VS Code extension per AGENTS.md specification
- OpenAI-style HTTP facade: POST /v1/chat/completions (SSE), GET /v1/models, GET /healthz
- JSON-RPC WebSocket server with methods: mcp.fs.read/list, mcp.search.code, mcp.symbols.list, mcp.edit.applyPatch, mcp.format.apply, mcp.imports.organize
- Copilot Chat integration via vscode.chat.requestChatAccess('copilot')
- Commands: bridge.enable/disable/status with status bar indicator
- Security: localhost-only binding, optional bearer token, read-only by default
- Policy enforcement via optional .agent-policy.yaml
- Ephemeral port management with globalState persistence

Co-Authored-By: Lars Baunwall <larslb@thinkability.dk>

vscode-bridge/node_modules/yaml/dist/stringify/stringifyNumber.d.ts

@@ -0,0 +1,2 @@
+import type { Scalar } from '../nodes/Scalar';
+export declare function stringifyNumber({ format, minFractionDigits, tag, value }: Scalar): string;