Merge origin/main with local pending work and update AGENTS.md references

- Resolve 14 conflicts from popping local stash on top of origin's
  eed1e88 + 8d3352f doc-comment additions (11 mechanical, plus
  version.rs, DashboardAuthenticatorTests.cs, DashboardGalaxyProjector.cs)
- Fix 4 test files that used AGENTS.md as the repo-root sentinel
  (now use CLAUDE.md, since AGENTS.md was removed in 4731ab5)
- Redirect 10 doc citations from AGENTS.md to the matching gateway.md
  sections (Value Model, Status Model, Security, STA Worker Thread
  Model, gRPC Layer rule, cancellation rule)

Verified: solution build clean, x86 worker build clean, 266/266
gateway tests passing, 121/121 worker tests passing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/MxGateway.Server/Dashboard/IDashboardAuthenticator.cs

@@ -11,6 +11,7 @@ public interface IDashboardAuthenticator
     /// <param name="apiKey">The API key to authenticate.</param>
     /// <param name="cancellationToken">Token to cancel the asynchronous operation.</param>
     Task<DashboardAuthenticationResult> AuthenticateAsync(
-        string? apiKey,
+        string? username,
+        string? password,
         CancellationToken cancellationToken);
 }