refactor: konsolidasi handler ke router.ts + complexity + test coverage
=== DRY Konsolidasi ===
- handleRelay, requireAuth, handleHealth, handleIndex, getClientIP → 1x di src/lib/router.ts
- api/relay.ts, src/worker.ts, src/index.ts jadi thin wrapper
=== Dead exports ===
- 35 dead exports dibersihkan (dari router.ts, worker.ts, relay.ts)
- Duplikasi simbol dari 12 ke 3 (wajar)
=== Keamanan ===
- Default API key sk-dummy-key dihapus — requireAuth return null saat key kosong
- Semua CORS konsisten via getCorsHeaders()
=== Kompleksitas ===
- handleRequest → pecah ke validateRelayTarget, createJsonErrorResponse, dll
- transformAnthropicStream (170 baris) → 4 sub-fungsi (emitInitEvents, emitDoneEvents, etc)
- handleAnthropicMessages → handleUpstreamError, buildStreamHeaders, buildJsonHeaders
- Fix duplicate stream? field di AnthropicRequest interface
=== Test Coverage ===
- Test naik dari 171 ke 248 (+77 test)
- File baru: src/router.test.ts (requireAuth, getClientIP, CORS, health, index)
- File baru: src/relay-integration.test.ts (filterResponseHeaders, shouldSendBody, buildRelayRequest, classifyFetchError, createRelayResponse, normalizeTargetUrl, SSRF, isPrivateIp)
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
