feat(gateway): add Feishu/Lark platform support (#3817)

Adds Feishu (ByteDance's enterprise messaging platform) as a gateway
platform adapter with full feature parity: WebSocket + webhook transports,
message batching, dedup, rate limiting, rich post/card content parsing,
media handling (images/audio/files/video), group @mention gating,
reaction routing, and interactive card button support.

Cherry-picked from PR #1793 by penwyp with:
- Moved to current main (PR was 458 commits behind)
- Fixed _send_with_retry shadowing BasePlatformAdapter method (renamed to
  _feishu_send_with_retry to avoid signature mismatch crash)
- Fixed import structure: aiohttp/websockets imported independently of
  lark_oapi so they remain available when SDK is missing
- Fixed get_hermes_home import (hermes_constants, not hermes_cli.config)
- Added skip decorators for tests requiring lark_oapi SDK
- All 16 integration points added surgically to current main

New dependency: lark-oapi>=1.5.3,<2 (optional, pip install hermes-agent[feishu])

Fixes #1788

Co-authored-by: penwyp <penwyp@users.noreply.github.com>

hermes_cli/gateway.py

@@ -1322,6 +1322,35 @@ _PLATFORMS = [
              "help": "The AppSecret from your DingTalk application credentials."},
         ],
     },
+    {
+        "key": "feishu",
+        "label": "Feishu / Lark",
+        "emoji": "🪽",
+        "token_var": "FEISHU_APP_ID",
+        "setup_instructions": [
+            "1. Go to https://open.feishu.cn/ (or https://open.larksuite.com/ for Lark)",
+            "2. Create an app and copy the App ID and App Secret",
+            "3. Enable the Bot capability for the app",
+            "4. Choose WebSocket (recommended) or Webhook connection mode",
+            "5. Add the bot to a group chat or message it directly",
+            "6. Restrict access with FEISHU_ALLOWED_USERS for production use",
+        ],
+        "vars": [
+            {"name": "FEISHU_APP_ID", "prompt": "App ID", "password": False,
+             "help": "The App ID from your Feishu/Lark application."},
+            {"name": "FEISHU_APP_SECRET", "prompt": "App Secret", "password": True,
+             "help": "The App Secret from your Feishu/Lark application."},
+            {"name": "FEISHU_DOMAIN", "prompt": "Domain — feishu or lark (default: feishu)", "password": False,
+             "help": "Use 'feishu' for Feishu China, or 'lark' for Lark international."},
+            {"name": "FEISHU_CONNECTION_MODE", "prompt": "Connection mode — websocket or webhook (default: websocket)", "password": False,
+             "help": "websocket is recommended unless you specifically need webhook mode."},
+            {"name": "FEISHU_ALLOWED_USERS", "prompt": "Allowed user IDs (comma-separated, or empty)", "password": False,
+             "is_allowlist": True,
+             "help": "Restrict which Feishu/Lark users can interact with the bot."},
+            {"name": "FEISHU_HOME_CHANNEL", "prompt": "Home chat ID (optional, for cron/notifications)", "password": False,
+             "help": "Chat ID for scheduled results and notifications."},
+        ],
+    },
 ]