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

packages/database/src/schema/meals.ts

@@ -74,6 +74,7 @@ export const mealBoxes = pgTable(
       .references(() => storageLocations.id),
     frozen: boolean("frozen").notNull().default(false),
     recommendedUseBy: date("recommended_use_by").notNull(),
+    leftoverSource: text("leftover_source"),
     reservedForUserId: uuid("reserved_for_user_id").references(() => users.id, {
       onDelete: "set null",
     }),

packages/database/src/schema/recipes.ts

@@ -1,5 +1,6 @@
 import {
   boolean,
+  date,
   doublePrecision,
   index,
   integer,
@@ -213,6 +214,12 @@ export const cookingSessions = pgTable(
     actualPortionsEaten: integer("actual_portions_eaten"),
     /** Förberedda rester efter sessionen (steg 3d). */
     leftoverEstimatePortions: integer("leftover_estimate_portions"),
+    /** Måltidsdatum (UTC) som rester/matlådor knyts till. */
+    mealDate: date("meal_date"),
+    /** Vilka meal_boxes som påverkades av sessionen och med hur mycket. */
+    mealBoxMutations: jsonb("meal_box_mutations").$type<
+      Array<{ mealBoxId: string; deltaPortions: number; frozen: boolean }>
+    >(),
     leftoverNote: text("leftover_note"),
     /** Ursprungligt FEFO-förslag, sparas för ev. undo/omräkning. */
     plannedDeductions: jsonb("planned_deductions").$type<