MCP v2: authenticated tools (MyOpenCRE, chat) matching REST authz

Follow-up to #1003

v1 (public stdio MCP, no auth) shipped in #1013 and is documented in docs/api/mcp.md. This ticket tracks the remaining product from #1003.

What

Expose authenticated OpenCRE REST through MCP with the same authz as REST (no MCP bypass secret).

Deferred from v1:

• MyOpenCRE GET/PUT /rest/v1/user/resources
• Chat POST /rest/v1/completion
• Admin / import tools
• Cookie / PAT / OAuth / session forwarding
• Extra public GETs still not in the allowlist (gap analysis, CSV, section path variants) — only if we still want them as tools

Constraints

• REST stays the execution and authorization boundary
• Fixed allowlist in application/mcp/catalog.py — OpenAPI membership alone must not expose a tool
• No credentials in tool arguments; no caller-supplied base URL / method / path
• Start from the existing stdio server (python -m application.mcp); remote transport is optional later

Parent: #1003 · v1 PR: #1013

Start with the existing stdio server via python -m application.mcp and inspect the fixed allowlist in application/mcp/catalog.py, then review the REST endpoints listed in the issue. The work is done when the selected MyOpenCRE and chat tools use REST authorization without credentials, caller-supplied routing, or an MCP bypass, while deferred admin and import tools remain out of scope.