test(flutter): re-enable drift tests after ci-flutter:1.26 ships libsqlite3-0

Drops the libsqlite3-missing skip cohort now that the ci-flutter
runner image installs libsqlite3-0 (CI-runner commit on its main).

Per-file removals (no behavior change in tests themselves — they
just stop being skipped):
- `@Tags(['drift'])` + `library;` directive from 5 files.
- `const _skipDrift = ...;` declaration + its rationale comment
  from 6 files (the 5 above + like_button_test.dart, which had its
  own _skipDrift for the rollback-via-drift case).
- `skip: _skipDrift` annotations from 17 test invocations across
  those 6 files (16 single-line + 1 multi-line in like_button).
- Stale `@Tags(['drift']) tier covers it` reference in
  home_screen_test.dart's drift-coverage comment.

Net -79 +18 lines across 7 files; 17 previously-silent tests are
now part of the CI signal. Fable #399.

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

flutter_client/test/cache/sync_controller_test.dart

@@ -1,6 +1,3 @@
-@Tags(['drift'])
-library;
-
 import 'package:dio/dio.dart';
 import 'package:drift/native.dart' show NativeDatabase;
 import 'package:flutter_riverpod/flutter_riverpod.dart';
@@ -11,15 +8,6 @@ import 'package:minstrel/cache/db.dart';
 import 'package:minstrel/cache/sync_controller.dart';
 import 'package:minstrel/library/library_providers.dart' show dioProvider;
 
-// SKIP NOTE (#357 plan B follow-up): drift's NativeDatabase needs the
-// system libsqlite3.so. The flutter-ci runner image doesn't ship it, so
-// every test in this file errors with "Failed to load dynamic library
-// 'libsqlite3.so'". Unblock by either:
-//   (a) adding libsqlite3-dev to the CI-Runner/CI-flutter image, or
-//   (b) using sqlite3/wasm + the wasm executor for VM tests.
-// Until then, real coverage lives in on-device verification.
-const _skipDrift = 'libsqlite3 missing on flutter-ci runner; on-device covers';
-
 /// Builds a Dio whose adapter resolves every request to the supplied
 /// status code + body. Avoids touching the network in tests.
 Dio _stubDio({required int status, dynamic body}) {
@@ -42,7 +30,7 @@ ProviderContainer _container({required AppDb db, required Dio dio}) {
 }
 
 void main() {
-  test('204 advances lastSyncAt without changing cursor', skip: _skipDrift, () async {
+  test('204 advances lastSyncAt without changing cursor', () async {
     final db = AppDb(NativeDatabase.memory());
     addTearDown(db.close);
 
@@ -56,7 +44,7 @@ void main() {
     expect(meta?.lastSyncAt, isNotNull);
   });
 
-  test('200 with artist upsert writes drift row + advances cursor', skip: _skipDrift, () async {
+  test('200 with artist upsert writes drift row + advances cursor', () async {
     final db = AppDb(NativeDatabase.memory());
     addTearDown(db.close);
 
@@ -85,7 +73,7 @@ void main() {
     expect(meta?.cursor, 7);
   });
 
-  test('200 with track delete removes the row', skip: _skipDrift, () async {
+  test('200 with track delete removes the row', () async {
     final db = AppDb(NativeDatabase.memory());
     addTearDown(db.close);
 
@@ -115,7 +103,7 @@ void main() {
     expect(track, isNull);
   });
 
-  test('like_track upsert + delete round-trip', skip: _skipDrift, () async {
+  test('like_track upsert + delete round-trip', () async {
     final db = AppDb(NativeDatabase.memory());
     addTearDown(db.close);