fix: MCP server polish — version, auth, errors, graceful degradation — Issue #445

[OneStepAt4time]

Summary

Fixes #445. M1.5 milestone.

Polish MCP server implementation.

Changes

1. VERSION from package.json — reads version dynamically at startup
2. Auth token forwarding — AEGIS_TOKEN env var forwarded to REST API
3. Error format consistency — MCP tool errors match REST API envelope (code, message, details)
4. Graceful degradation — clear error when REST server down, no crash

Not included

• Streamable HTTP transport — deferred to separate issue (requires more design)

Test plan

• tsc --noEmit — clean
• npm run build — clean
• npm test — 65 files, 1534 tests passing