Retire only the API cache when its version changes (PR #97 review F2, F3)

F2: one shared cache version renamed every cache, so the v2 bump that
drops the v1 API cache (dinner responses with the pasted recipe_url) also
deleted saved photos, fonts and the precache. Each cache now carries its
own version in cacheVersions; only api is v2, so activate deletes
mealquest-api-v1 and keeps mealquest-precache-v1, -media-v1 and -fonts-v1.

F3: replace the source-text activation test with src/sw.test.ts, which
loads the worker with the Workbox precache and router stubbed, dispatches
activate against mocked Cache Storage, and asserts caches.delete is called
for mealquest-api-v1 only. tsconfig.sw.json type-checks the test with the
worker's types.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/tsconfig.sw.json

@@ -4,6 +4,6 @@
     "lib": ["ES2022", "WebWorker"],
     "types": []
   },
-  "include": ["src/sw.ts"],
+  "include": ["src/sw.ts", "src/sw.test.ts"],
   "exclude": []
 }