Inspect authoritative Git remote state

docs/internal/overview.md

@@ -17,6 +17,8 @@ Implemented internal packages:
 - `internal/candidate` captures and validates one clean local candidate, checks
   its committed release note and local tag state, runs validation once, and
   rechecks mutable repository state.
+- `internal/git` resolves one effective push destination, applies it to a
+  command-scoped remote, and reads exact authoritative branch and tag refs.
 - `cmd/releasekit/internal/cli` parses implemented commands, loads strict JSON
   profiles, and adapts configured checks to the process runner.
 

docs/roadmap/implementation.md

@@ -567,7 +567,7 @@ diagnostic. Temporary Git repositories cover the acceptance cases; offline
 
 ## Stage 6: Resolve and inspect the authoritative endpoint
 
-Status: Pending. Depends on Stage 5.
+Status: Complete. Depends on Stage 5.
 
 1. Implement effective push-URL capture, command-scoped remote configuration,
    matching read/write resolution, and endpoint rechecks described above.
@@ -581,6 +581,14 @@ ordinary URL rewrites, multiple push destinations, missing main, conflicting
 tags, main ahead/behind the candidate, endpoint changes, and remote failure.
 Queries leave local tags, persistent remote configuration, and remote refs intact.
 
+Evidence: `internal/git` captures effective push destinations through Git,
+rejects multiple distinct destinations, verifies scoped URL rewriting, and
+queries exact main and version-tag refs. A candidate check requires main to
+equal the captured commit and the version tag to be absent. Local bare remote
+tests cover separate fetch/push URLs, both rewrite modes, missing main, an
+existing tag, main ahead and behind, endpoint changes, unreadable remote state,
+and unchanged persistent config and refs.
+
 ## Stage 7: Create and push the exact annotated tag
 
 Status: Pending. Depends on Stage 6.