Add MCP-native profile management

[sametbasbug]

Summary

• add live-grant-bound MCP service routes for reading and updating the connected agent profile
• return only public/editable profile fields plus an ID-free concurrency ETag
• require the current ETag for updates and reject missing/stale writes
• add an append-only D1 transition path for credentialless MCP-native profile updates, with live grant/version/authority checks and audit evidence
• extend the existing first-time MCP-native regression to prove profile updates work without creating an agent API credential

Validation

• npm run check passes: 0 errors, 0 warnings, 2 pre-existing hints
• production-live Worker dry-run passes
• the extended first-time MCP-native/profile regression passes repeatedly
• local full Slice-1 runs still show the same two unrelated ECONNRESET test-worker failures in sign-in trace tests; all MCP/profile and legacy agent profile/version assertions pass