feat: v0.5.16 - migrate to Responses API (#586)

* refactor: migrate from /v1/runs to /v1/responses streaming API

Replace EventSource-based polling with direct SSE streaming via the
/v1/responses endpoint across all server-side callers (chat-run-socket,
context-compressor, gateway-client, agent-clients). Messages are now
written to DB in real-time during streaming, eliminating post-run sync.
Frontend chat store adds tool_call_id tracking for deduplication.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* chore: bump version to 0.5.16 and add changelog

- Persist real API usage to usage table on response.completed
- Remove unused codex_reasoning_items field from message schema
- Fix unused variable warnings in chat-run-socket
- Bump version to 0.5.16
- Add changelog entries for 0.5.16 (8 locales)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hermes-web-ui",
-  "version": "0.5.15",
+  "version": "0.5.16",
   "description": "Self-hosted AI chat dashboard for Hermes Agent — multi-model (Claude, GPT, Gemini, DeepSeek) web UI with Telegram, Discord, Slack, WhatsApp integration",
   "repository": {
     "type": "git",