feat(3d): meal-box merge, stored mutations, undo, mobile undo UI + i18n ×12

- Merge leftovers into existing meal_box when same recipeId + cookedAt date + frozen + available.
- Store mealBoxMutations JSONB on cooking_sessions for deterministic undo.
- Undo decrements portions/remaining, discards box at zero, appends correction ledger rows.
- Mobile: undo button in cooking/[id].tsx after-flow and meal-boxes.tsx within 24h window.
- i18n undo strings across all 12 locales; parity test green.
- 6 new integration tests: merge, no cross-date merge, frozen split, undo restore, undo discard, ledger invariant.
- Update FAS3 audit doc with 3d semantics.

Closes Fas 3d

infrastructure/migrations/meta/_journal.json

@@ -99,6 +99,34 @@
       "when": 1786055900000,
       "tag": "0014_expand_event_types",
       "breakpoints": true
+    },
+    {
+      "idx": 14,
+      "version": "7",
+      "when": 1786056300000,
+      "tag": "0015_meal_box_leftover_source",
+      "breakpoints": true
+    },
+    {
+      "idx": 15,
+      "version": "7",
+      "when": 1786056400000,
+      "tag": "0016_expand_event_types_meal_box_updated",
+      "breakpoints": true
+    },
+    {
+      "idx": 16,
+      "version": "7",
+      "when": 1786056500000,
+      "tag": "0017_cooking_sessions_meal_date",
+      "breakpoints": true
+    },
+    {
+      "idx": 17,
+      "version": "7",
+      "when": 1786056600000,
+      "tag": "0018_cooking_sessions_meal_box_mutations",
+      "breakpoints": true
     }
   ]
 }