chore(01-01): scaffold Flutter project with all dependencies and tooling

- Flutter project created with flutter create (Android platform)
- Runtime deps: flutter_riverpod, riverpod_annotation, drift 2.31, drift_flutter, go_router, path_provider, shared_preferences, flutter_localizations, intl
- Dev deps: riverpod_generator, drift_dev 2.31, build_runner
- Pinned drift/drift_dev to 2.31 for analyzer ^9.0.0 compatibility with riverpod_generator
- Configured l10n.yaml, build.yaml (Drift), analysis_options.yaml (riverpod_lint)
- Minimal ARB file for localization tooling to resolve

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

build.yaml

@@ -0,0 +1,11 @@
+targets:
+  $default:
+    builders:
+      drift_dev:
+        options:
+          databases:
+            household_keeper: lib/core/database/database.dart
+          sql:
+            dialect: sqlite
+            options:
+              version: "3.38"