feat: dish recognition job context, diary linkage, home widget, history page

Backend:
- Rename recognition_jobs → dish_recognition_jobs; add target_date and
  target_meal_type columns to capture scan context at submission time
- Add job_id FK on meal_diary so entries are linked to their origin job
- New GET /ai/jobs endpoint returns today's unlinked jobs for the current user
- diary.Entry and CreateRequest gain job_id field; repository reads/writes it
- CORS middleware: allow Accept-Language and Cache-Control headers
- Logging middleware: implement http.Flusher on responseWriter (needed for SSE)
- Consolidate migrations into a single 001_initial_schema.sql

Flutter:
- POST /ai/recognize-dish now sends target_date and target_meal_type
- DishResultSheet accepts jobId; _addToDiary includes it in the diary payload,
  saves last-used meal type to SharedPreferences, invalidates todayJobsProvider
- TodayJobsNotifier + todayJobsProvider: loads unlinked jobs via GET /ai/jobs
- Home screen shows _TodayJobsWidget (up to 3 tiles) between macros and meals;
  tapping a done tile reopens DishResultSheet with the stored result
- Quick Actions row: third button "История" → /scan/history
- New RecognitionHistoryScreen: full-screen list of today's unlinked jobs
- LocalPreferences wrapper over SharedPreferences (last_used_meal_type)
- app_theme: apply Google Fonts Roboto as default font family

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

client/lib/core/storage/local_preferences.dart

@@ -0,0 +1,17 @@
+import 'package:shared_preferences/shared_preferences.dart';
+
+/// Thin wrapper over SharedPreferences for app-level local settings.
+class LocalPreferences {
+  const LocalPreferences(this._prefs);
+
+  final SharedPreferences _prefs;
+
+  static const _keyLastUsedMealType = 'last_used_meal_type';
+
+  /// Returns the last meal type the user selected when adding to diary, or null.
+  String? getLastUsedMealType() => _prefs.getString(_keyLastUsedMealType);
+
+  /// Persists the last used meal type.
+  Future<void> setLastUsedMealType(String mealTypeId) =>
+      _prefs.setString(_keyLastUsedMealType, mealTypeId);
+}

client/lib/core/storage/local_preferences_provider.dart

@@ -0,0 +1,9 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'local_preferences.dart';
+
+/// Provider for [LocalPreferences]. Must be overridden in [ProviderScope]
+/// after SharedPreferences is initialised in main().
+final localPreferencesProvider = Provider<LocalPreferences>(
+  (ref) => throw UnimplementedError('localPreferencesProvider not overridden'),
+);