feat(inventory): naturlig-språklig fritextsökning med FoodTwin-fakta, trust-hedge och i18n ×12

- Nytt endpoint GET /v1/inventory/natural-search.
- Robust matchning med unaccent + pg_trgm similarity mot display_name,
  brand och kanoniska ingrediensnamn (sv/en).
- Svar byggs deterministiskt från faktisk data: lagringsplats + sublocation
  om registrerad, trust-state-hedge från befintlig trust-motor.
- Server-sidan i18n-katalog för 12 språk.
- Tester för svensk träff och noll-träff på flera språk.
- Design-dokument docs/30-sökrobusthet-matvaror.md.

apps/api/src/routes/inventory.ts

@@ -4,6 +4,7 @@ import { schema } from "@app/database";
 import {
   createInventoryItemInputSchema,
   idParamSchema,
+  inventoryNaturalSearchQuerySchema,
   inventoryQuerySchema,
   inventoryTransactionInputSchema,
   updateInventoryItemInputSchema,
@@ -22,6 +23,8 @@ import {
   requireActiveHousehold,
   requireMembership,
 } from "../lib/helpers.js";
+import { buildNaturalSearchResponse } from "../lib/inventorySearchResponse.js";
+import { userLanguageTag } from "../lib/contentLanguage.js";
 
 /**
  * Food Twin – lagret (spec §8). Transaktionsbaserat: varje förändring skrivs
@@ -139,6 +142,115 @@ export async function inventoryRoutes(app: FastifyInstance) {
     };
   });
 
+  /**
+   * Naturlig-språklig fritextsökning i lagret (FoodTwin + trust-hedge).
+   * Returnerar både strukturerade träffar och ett mänskligt svar.
+   */
+  app.get("/v1/inventory/natural-search", auth, async (req) => {
+    const query = parse(inventoryNaturalSearchQuerySchema, req.query);
+    const householdId = await requireActiveHousehold(app.db, req.userId);
+    const decayProfile = await getActiveDecayProfile(app.db);
+    const languageTag = query.languageTag ?? (await userLanguageTag(app.db, req.userId));
+
+    const q = query.q;
+    const pattern = `%${q}%`;
+    const similarityThreshold = 0.15;
+
+    const rows = await app.db
+      .select({
+        item: schema.inventoryItems,
+        locationType: schema.storageLocations.type,
+        locationName: schema.storageLocations.name,
+        shelfLife: schema.canonicalIngredients.shelfLifeGuidance,
+      })
+      .from(schema.inventoryItems)
+      .innerJoin(
+        schema.storageLocations,
+        eq(schema.inventoryItems.storageLocationId, schema.storageLocations.id),
+      )
+      .leftJoin(
+        schema.canonicalIngredients,
+        eq(schema.inventoryItems.canonicalIngredientId, schema.canonicalIngredients.id),
+      )
+      .where(
+        and(
+          eq(schema.inventoryItems.householdId, householdId),
+          isNull(schema.inventoryItems.depletedAt),
+          gt(schema.inventoryItems.quantity, 0),
+          or(
+            sql`unaccent(${schema.inventoryItems.displayName}) ILIKE unaccent(${pattern})`,
+            sql`similarity(${schema.inventoryItems.displayName}, ${q}) > ${similarityThreshold}`,
+            sql`unaccent(${schema.canonicalIngredients.nameSv}) ILIKE unaccent(${pattern})`,
+            sql`unaccent(${schema.canonicalIngredients.nameEn}) ILIKE unaccent(${pattern})`,
+            sql`similarity(${schema.canonicalIngredients.nameSv}, ${q}) > ${similarityThreshold}`,
+            sql`similarity(${schema.canonicalIngredients.nameEn}, ${q}) > ${similarityThreshold}`,
+            sql`unaccent(${schema.inventoryItems.brand}) ILIKE unaccent(${pattern})`,
+          )!,
+        ),
+      )
+      .orderBy(
+        desc(
+          sql`GREATEST(
+            similarity(${schema.inventoryItems.displayName}, ${q}),
+            similarity(${schema.canonicalIngredients.nameSv}, ${q}),
+            similarity(${schema.canonicalIngredients.nameEn}, ${q})
+          )`,
+        ),
+      )
+      .limit(query.limit);
+
+    const resultItems = rows.map((r) => {
+      const expiry = classifyExpiry({
+        bestBeforeDate: r.item.bestBeforeDate,
+        useByDate: r.item.useByDate,
+        openedAt: r.item.openedAt,
+        frozenAt: r.item.frozenAt,
+        thawedAt: r.item.thawedAt,
+        purchasedAt: r.item.purchasedAt,
+        storageLocationType: r.locationType,
+        shelfLifeGuidance: r.shelfLife,
+      });
+      const trust = computeTrust(
+        {
+          confidence: r.item.confidence,
+          verifiedByUser: r.item.verifiedByUser,
+          lastVerifiedAt: r.item.lastVerifiedAt,
+          quantity: r.item.quantity,
+          updatedAt: r.item.updatedAt,
+        },
+        new Date(),
+        decayProfile,
+      );
+      return {
+        ...r.item,
+        locationName: r.locationName,
+        locationType: r.locationType,
+        expiry,
+        trustState: trust.state,
+        trustScore: trust.score,
+      };
+    });
+
+    const naturalItems = resultItems.map((item) => ({
+      displayName: item.displayName,
+      quantity: item.quantity,
+      unit: item.unit,
+      locationName: item.locationName,
+      locationType: item.locationType,
+      sublocation: item.sublocation,
+      trustState: item.trustState,
+      trustScore: item.trustScore,
+    }));
+
+    const response = buildNaturalSearchResponse(naturalItems, languageTag);
+
+    return {
+      query: q,
+      response,
+      items: resultItems,
+    };
+  });
+
   /** Varor som bör användas snart – driver "använd först" (spec §4.4, §40). */
   app.get("/v1/inventory/expiring", auth, async (req) => {
     const householdId = await requireActiveHousehold(app.db, req.userId);