docs(android): record SonarQube coverage wiring and issue triage (§12.1)

Add §12.1 documenting the Android-app SonarQube setup: the coverage gate
failed at 0% because the source-only scan received no JaCoCo report (a
reporting gap, not a testing gap). Records the JaCoCo wiring (jacoco plugin +
report task, sonar.coverage.jacoco.xmlReportPaths, pure-UI coverage
exclusions, a Gradle step in sonarqube.yml) and the 2026-07-22 triage:
3 smells fixed in code, 12 marked Won't Fix (snake_case DTO fields that
mirror the wire contract; idiomatic Compose/nav complexity).

Pairs with RunicGateway/Android-app chore/sonar-coverage-and-cleanup.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NgyHnrNa8WwG3doxvxjuCr

android/PLAN.md

@@ -995,6 +995,29 @@ repos use), on a bare `ubuntu:latest` container.
   signing identity stable from the first release (Play later requires consistency).
 - Semantic `versionName` + monotonic `versionCode`; tag releases.
 
+### 12.1 Code quality — SonarQube (`Runic-Gateway-Android-app`)
+
+Analysis runs post-merge and non-blocking (`.gitea/workflows/sonarqube.yml`); the gate is
+informational. The project is clean (0 bugs / 0 vulns / 0 hotspots, Maintainability **A**); the only
+gate failure is **coverage = 0% on new code**, which is a *reporting* gap, not a testing gap — the
+25-file JVM unit suite exists, but the source-only Sonar scan never received a JaCoCo report.
+
+**Coverage wiring (the fix):**
+- Apply the `jacoco` plugin in `app/build.gradle.kts` + a `jacocoTestReport` task fed by
+  `testDebugUnitTest`, emitting XML. Exclude generated/DI/Compose scaffolding
+  (`**/*_Hilt*`, `**/*_Factory*`, `**/di/**`, `**/*ComposableSingletons*`, `R`/`BuildConfig`).
+- `sonar-project.properties`: set `sonar.coverage.jacoco.xmlReportPaths` to the report, and
+  `sonar.coverage.exclusions` for pure-`@Composable` UI (JVM unit tests can't execute composable
+  bodies without Robolectric, so counting those lines would unfairly sink new-code coverage).
+- `sonarqube.yml` must now run a real Gradle build before the scan (JDK 17 + Android SDK, mirroring
+  `pr-checks.yml`): `./gradlew testDebugUnitTest jacocoTestReport` → then the scan step.
+
+**Issue triage (2026-07-22):** of 15 code smells, **3 fixed in code** — remove an unused import
+(`AdminContentScreen.kt`), remove an unused `page` param (`AdminSupportScreen.RespondDialog`), and
+decompose `LoginViewModel` (cognitive complexity 20). The remaining **12 marked *Won't Fix*** via the
+Sonar API with rationale: 5 snake_case DTO fields (intentionally mirror the JSON wire contract) and 7
+Compose/nav cognitive-complexity + hoisted-callback param-count smells (idiomatic for Jetpack Compose).
+
 ## 13. Open questions (revisit as we go)
 
 **Decided (recorded here for context):** single shard per install (§3); native auth is