fix: resolve Bun mock isolation contamination across test files

- storage.service.ts: use dynamic import() inside each function so the
  current @aws-sdk mock is always picked up regardless of module load order
- images.test.ts + image.service.test.ts: replace module-level storage.service
  mock with @aws-sdk/client-s3 mock to avoid contaminating storage.service.test.ts
- routes/auth.test.ts: remove unnecessary oauth.service mock (no test uses
  verifyAccessToken) which was contaminating oauth.service.test.ts
- middleware/auth.test.ts: complete oauth.service mock shape with all exports

All 464 tests now pass in a single bun test run.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/routes/auth.test.ts

@@ -12,11 +12,6 @@ mock.module("@hono/oidc-auth", () => ({
 	revokeSession: async () => {},
 }));
 
-// Mock verifyAccessToken from oauth.service
-mock.module("../../src/server/services/oauth.service", () => ({
-	verifyAccessToken: mock(() => Promise.resolve(null)),
-}));
-
 // Import routes AFTER mocks
 const { authRoutes } = await import("../../src/server/routes/auth.ts");