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/middleware/auth.test.ts

@@ -12,10 +12,17 @@ mock.module("@hono/oidc-auth", () => ({
 	revokeSession: async () => {},
 }));
 
-// Mock verifyAccessToken from oauth.service
+// Mock oauth.service — all exports included so later test files don't see
+// a partial module shape when Bun's module registry is shared across files.
 const mockVerifyAccessToken = mock(() => Promise.resolve(false));
 mock.module("../../src/server/services/oauth.service", () => ({
 	verifyAccessToken: mockVerifyAccessToken,
+	registerClient: mock(() => Promise.resolve({ clientId: "id" })),
+	getClient: mock(() => Promise.resolve(null)),
+	createAuthorizationCode: mock(() => Promise.resolve({ code: "code" })),
+	exchangeCode: mock(() => Promise.resolve(null)),
+	refreshAccessToken: mock(() => Promise.resolve(null)),
+	cleanExpiredOAuthData: mock(() => Promise.resolve()),
 }));
 
 // Import middleware AFTER mocks are set up