feat: unified food calendar — extend home screen to future dates + planned meals

Phase 1: date strip now covers today + 7 future days; right chevron enabled;
future pills rendered in lighter style.

Phase 2: home screen shows DateContext (past/today/future):
- future dates: hide calorie ring + macros, show PlanningBanner
- plannedMealsProvider derives from cached menuProvider (no extra API call)
- _MealCard shows ghost PlannedSlotTile for unconfirmed menu slots
- "Mark as eaten" creates a diary entry (source: menu_plan) via existing API

New l10n keys (12 locales): planningForDate, markAsEaten, plannedMealLabel

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

client/lib/l10n/app_pt.arb

@@ -123,5 +123,13 @@
   },
   "servingsLabel": "Porções",
   "addToDiary": "Adicionar ao diário",
-  "scanDishPhoto": "Escanear foto"
+  "scanDishPhoto": "Escanear foto",
+  "planningForDate": "",
+  "@planningForDate": {
+    "placeholders": {
+      "date": { "type": "String" }
+    }
+  },
+  "markAsEaten": "",
+  "plannedMealLabel": ""
 }