docs(progress): clarify Section 3.1 Android build failure

Section 3.1 fails due to Capacitor plugin architecture constraint, not missing Android SDK.

Clarification:
- Error: 'Capacitor Android project not found'
- Reason: Capacitor plugins cannot be built standalone
- Expected: This is normal behavior for Capacitor plugins
- Solution: Build from test-app or integrated Capacitor app

This is an architectural constraint, not a code issue. The runbook should note that Android build verification requires a Capacitor app context.

docs/progress/PRODUCTION-READINESS-EXECUTION-LOG.md

@@ -70,8 +70,12 @@
 
 9. **Section 3.1: Android build** ⚠️
    - **Date:** 2025-12-24
-   - **Result:** BUILD FAILED (expected on Linux without Android SDK)
-   - **Note:** Requires Android SDK environment. Build check should be run on Android-capable system.
+   - **Result:** BUILD FAILED (expected - Capacitor plugins cannot be built standalone)
+   - **Error:** `ERROR: Capacitor Android project not found`
+   - **Note:** This is expected behavior. Capacitor plugins require a Capacitor Android project context to build. The error message indicates:
+     - Build from `test-apps/android-test-app` (recommended)
+     - Or include plugin in a Capacitor app's `android/settings.gradle`
+   - **Verification:** Should be tested from test-app or integrated Capacitor app, not standalone.
 
 10. **Section 3.3: Android rolling window logic** ✅
     - **Date:** 2025-12-24