fix(diagnostics): StateFlow distinctUntilChanged build error + AdminUser test fixtures

- DiagnosticsReporter.collectServerHealth: drop distinctUntilChanged() on
  networkStatus.state (StateFlow is already distinct; the deprecation
  warning is a hard error under allWarningsAsErrors).
- web users.test.ts: add debug_mode_enabled to the alice/bob AdminUser
  fixtures now that the field is required on the type.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K55iTxn95BtshocgdE1shW

android/app/src/main/java/com/fabledsword/minstrel/diagnostics/DiagnosticsReporter.kt

@@ -127,7 +127,9 @@ class DiagnosticsReporter @Inject constructor(
     }
 
     private suspend fun collectServerHealth() {
-        networkStatus.state.distinctUntilChanged().collect { s ->
+        // state is a StateFlow — already conflated/distinct, so no
+        // distinctUntilChanged (it's a deprecation warning = build error).
+        networkStatus.state.collect { s ->
             record("connectivity", buildJsonObject {
                 put("event", "server_health")
                 put("state", s.name)