test(platform-service): align getAllProducts test with invttrdg fallback

CI run 67 surfaced a real test failure:

  src/modules/products/cache.test.ts:104
    getAllProducts > returns all cached products
    expected [ { id: 'lysnrai', …(11) }, …(2) ] to have a length of 2
    but got 3

Root cause: cache.ts has a TEMPORARY_FALLBACK_PRODUCTS map (currently
just 'invttrdg') that getAllProducts() merges into its return value
on top of the loaded cache. The test fixture loads 2 products
(lysnrai, mindlyst), so the actual return is 3 — the test was
written before the fallback shim landed and never got updated.

Two ways to reconcile: (a) make the test reflect today's behaviour,
or (b) gut the fallback. The cache.ts comment explicitly marks
the fallback as 'TODO(platform): remove after creating the real
product …', so the right move is (a): keep the shim in place and
make the test enforce the documented contract.

  - assertion now: toHaveLength(3) + .toContain('invttrdg')
  - inline comment ties the expectation back to cache.ts so a
    future cleanup removing the fallback will obviously need to
    drop it back to 2

Verified locally:
  pnpm vitest run cache.test.ts   -> 8/8 pass

services/platform-service/src/modules/products/cache.test.ts

@@ -9,7 +9,13 @@ vi.mock('./repository.js', () => ({
 }));
 
 import { getAll } from './repository.js';
-import { loadProductCache, getProduct, isValidProduct, getAllProducts, cacheSize } from './cache.js';
+import {
+  loadProductCache,
+  getProduct,
+  isValidProduct,
+  getAllProducts,
+  cacheSize,
+} from './cache.js';
 
 const mockGetAll = vi.mocked(getAll);
 
@@ -97,13 +103,19 @@ describe('product cache', () => {
   });
 
   describe('getAllProducts', () => {
-    it('returns all cached products', async () => {
+    it('returns all cached products (plus temporary fallback products)', async () => {
       mockGetAll.mockResolvedValue(products);
       await loadProductCache();
       const all = getAllProducts();
-      expect(all).toHaveLength(2);
+      // The cache holds 2 products (lysnrai, mindlyst) and getAllProducts()
+      // additionally injects entries from TEMPORARY_FALLBACK_PRODUCTS that
+      // are not already in the cache. Today that set is { invttrdg }, so
+      // the total is 3. When the invttrdg fallback is removed (see
+      // cache.ts TODO), this expectation should drop back to 2.
+      expect(all).toHaveLength(3);
       expect(all.map(p => p.id)).toContain('lysnrai');
       expect(all.map(p => p.id)).toContain('mindlyst');
+      expect(all.map(p => p.id)).toContain('invttrdg');
     });
   });