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/recognition/job.go

@@ -20,18 +20,31 @@ const (
 	TopicFree = "ai.recognize.free"
 )
 
-// Job represents an async dish recognition task stored in recognition_jobs.
+// Job represents an async dish recognition task stored in dish_recognition_jobs.
 type Job struct {
-	ID          string
-	UserID      string
-	UserPlan    string
-	ImageBase64 string
-	MimeType    string
-	Lang        string
-	Status      string
-	Result      *ai.DishResult
-	Error       *string
-	CreatedAt   time.Time
-	StartedAt   *time.Time
-	CompletedAt *time.Time
+	ID             string
+	UserID         string
+	UserPlan       string
+	ImageBase64    string
+	MimeType       string
+	Lang           string
+	TargetDate     *string // nullable YYYY-MM-DD
+	TargetMealType *string // nullable e.g. "lunch"
+	Status         string
+	Result         *ai.DishResult
+	Error          *string
+	CreatedAt      time.Time
+	StartedAt      *time.Time
+	CompletedAt    *time.Time
+}
+
+// JobSummary is a lightweight job record for list endpoints (omits ImageBase64).
+type JobSummary struct {
+	ID             string         `json:"id"`
+	Status         string         `json:"status"`
+	TargetDate     *string        `json:"target_date,omitempty"`
+	TargetMealType *string        `json:"target_meal_type,omitempty"`
+	Result         *ai.DishResult `json:"result,omitempty"`
+	Error          *string        `json:"error,omitempty"`
+	CreatedAt      time.Time      `json:"created_at"`
 }