feat: add batch-cooking generation entry point to meal planner

Adds a "Batch cooking" button next to "Generate with AI" on the meal
plan page, opening the same wizard used on /batch-cooking. Closes the
loop on the original ask: batch-cooking sessions can now be started
directly from the meal planner, not just from the recipes list.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/messages/en.json

@@ -677,6 +677,7 @@
     "weekOf": "Week of {date}",
     "sharedMealPlanTitle": "{name}'s Meal Plan",
     "batchCookBadge": "Batch cooking",
+    "batchCooking": "Batch cooking",
     "pickDishTitle": "Which dish from \"{recipe}\"?",
     "pickDishDescription": "This is a batch-cooking session — pick the specific dish for this slot.",
     "back": "Back",

apps/web/messages/fr.json

@@ -665,6 +665,7 @@
     "weekOf": "Semaine du {date}",
     "sharedMealPlanTitle": "Planning repas de {name}",
     "batchCookBadge": "Batch cooking",
+    "batchCooking": "Batch cooking",
     "pickDishTitle": "Quel plat de \"{recipe}\" ?",
     "pickDishDescription": "C'est une session de batch cooking — choisissez le plat précis pour ce créneau.",
     "back": "Retour",