Simplify auth and search client, drop local JWT expiry tracking

Auth:
- Remove jwt.ts — stop decoding JWT exp claims locally
- Simplify OTP login: direct token extraction from verify response,
  remove CookieJar, BFS token extraction, session fallback, CF bypass
- Storage: drop expires field, store token-only; clear on 401/403
- Single auth path: try stored token → macOS app → OTP fallback

Search client:
- Remove Cloudflare subprocess fallback (fetchViaBunRuntime)
- Remove streamFromText, isCloudflareChallenge, BunFetchResult
- Simplify SSE fetch to single fetch() call with abort signal
- Let server validate tokens; clear cache on auth errors

Render:
- Extract shared utilities (asString, truncate) to render/util.ts
- Simplify call.ts and result.ts to import from shared module

Tests:
- Remove jwt.test.ts (module deleted)
- Add otp-flow.test.ts for email OTP authentication
- Simplify login and client tests for reduced code paths

Add debug scripts and plan documents.

.gitignore

@@ -1,2 +1,4 @@
 node_modules/
 .env
+local_tests/
+[Pp][Ll][Aa][Nn].[Mm][Dd]