chore(release): v3.6.5 — Claude Code native parity, Antigravity credit fallback, 5 community PRs

## New Features
- Claude Code Native Parity: CCH xxHash64 signing, TitleCase tool remapping,
  API constraint enforcement (PR #1188 — @RaviTharuma)
- Antigravity AI Credits Fallback: auto-retry with GOOGLE_ONE_AI credit
  injection on quota exhaustion (PR #1190 — @sFaxsy)
- Per-Connection Codex Defaults (PR #1176 — @rdself)
- xxhash-wasm dependency for CCH signing

## Bug Fixes
- Search cache coalescing with TTL=0 (PR #1178 — @sjhddh)
- Antigravity credit cache key alignment (PR #1190)
- Codex combo smoke test false positives (PR #1176)
- Electron NODE_PATH resolution on Windows (PR #1172 — @backryun)
- CC-compatible test assertion fix (billing header cache_control)

## Breaking Changes
- DELETE /api/settings/codex-service-tier removed (PR #1176)
- CCH signing on CC-compatible providers

Tests: 2770/2770 passing

docs/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: OmniRoute API
-  version: 3.6.4
+  version: 3.6.5
   description: |
     OmniRoute is a local-first AI API proxy router. It provides an OpenAI-compatible
     endpoint that routes requests to multiple AI providers with load balancing,