chore: batch fix final-review findings on Plan 01

- ROADMAP: mark v0.1 (Foundation & CI) as complete
- REQUIREMENTS: move Foundation & CI from Active to Validated (shipped)
- AndroidManifest: drop redundant android:label and android:theme on
  MainActivity - both inherited from <application>
- build.gradle.kts: move ui-tooling-preview to debugImplementation
  (@Preview annotations are dev-only; release APK stays smaller)

All foundation verification (lint + test + assembleDebug) still green.

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

.planning/ROADMAP.md

@@ -4,7 +4,7 @@
 
 | Version | Milestone | Status |
 |---|---|---|
-| v0.1 | Foundation & CI | in progress |
+| v0.1 | Foundation & CI | complete |
 | v0.2 | Data Layer & Permission Flow | pending |
 | v0.3 | Month view | pending |
 | v0.4 | Week view | pending |