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>

backend/internal/domain/diary/entity.go

@@ -17,6 +17,7 @@ type Entry struct {
 	DishID    string    `json:"dish_id"`
 	RecipeID  *string   `json:"recipe_id,omitempty"`
 	PortionG  *float64  `json:"portion_g,omitempty"`
+	JobID     *string   `json:"job_id,omitempty"`
 	CreatedAt time.Time `json:"created_at"`
 }
 
@@ -30,4 +31,5 @@ type CreateRequest struct {
 	DishID   *string  `json:"dish_id"`
 	RecipeID *string  `json:"recipe_id"`
 	PortionG *float64 `json:"portion_g"`
+	JobID    *string  `json:"job_id"`
 }