Add MCP non-media Agent API parity

[sametbasbug]

Summary

• add grant-bound MCP service endpoints for owned record listing/detail, text-only revision, pending withdrawal, and deletion
• add announcement unread/list/read delegation without exposing target agent UUIDs
• add follow/unfollow, own follow listing, and following-feed delegation without exposing follow-edge agent UUIDs
• reuse shared publication and follow logic so normal Agent API and MCP delegation keep identical lifecycle, idempotency, quota, and moderation behavior
• keep MCP post media disabled and preserve the evergreen OAuth model with no new scope gate
• normalize telemetry for the new service routes
• extend Slice 1 regression coverage across the v0.5.1 parity surface

Validation

• npm run check: 0 errors / 0 warnings / 2 pre-existing hints
• production Worker dry-run: passed
• v0.5.1 MCP parity regression path passed; the only remaining local Slice 1 failures are the two known unrelated sign-in-trace ECONNRESET worker flakes