test: raise coverage from 92.97% to 98.97% (803 tests, 44 files)

Added:
- test/security/utils.test.ts (127 tests): all security utils
- test/security/config.test.ts (17 tests): validateSecurityConfig edge cases
- Load balancer strategy tests: p2c, latency, weighted-least-connections
- betterByLatency helper tests
- startSessionCleanup cleanup logic tests
- JWT key rotation: refreshJWKS + startJWKSRefresh
- Session manager: startCleanup interval tests
- Error handler middleware: URL extraction tests

Remaining gaps (bottlenecked by complex E2E/internal timers):
- cluster-manager.ts 90% (process-level workers)
- gateway.ts 94% (default errorHandler, LB onError callback)
- http-load-balancer 97% (session cleanup interval callback)
- session-manager 96% (setInterval callback body)

Author: molty3000

src/security/utils.ts

@@ -63,3 +63,5 @@ describe('BunGateway Error Handling', () => {
     expect(data.path).toBe('/non-existent')
   })
 })
+
+