feat(gateway): add WeCom (Enterprise WeChat) platform support (#3847)

Adds WeCom as a gateway platform adapter using the AI Bot WebSocket
gateway for real-time bidirectional communication. No public endpoint
or new pip dependencies needed (uses existing aiohttp + httpx).

Features:
- WebSocket persistent connection with auto-reconnect (exponential backoff)
- DM and group messaging with configurable access policies
- Media upload/download with AES decryption for encrypted attachments
- Markdown rendering, quote context preservation
- Proactive + passive reply message modes
- Chunked media upload pipeline (512KB chunks)

Cherry-picked from PR #1898 by EvilRan with:
- Moved to current main (PR was 300 commits behind)
- Skipped base.py regressions (reply_to additions are good but belong
  in a separate PR since they affect all platforms)
- Fixed test assertions to match current base class send() signature
  (reply_to=None kwarg now explicit)
- All 16 integration points added surgically to current main
- No new pip dependencies (aiohttp + httpx already installed)

Fixes #1898

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

hermes_cli/tools_config.py

@@ -142,6 +142,7 @@ PLATFORMS = {
     "matrix":   {"label": "💬 Matrix",     "default_toolset": "hermes-matrix"},
  "dingtalk": {"label": "💬 DingTalk", "default_toolset": "hermes-dingtalk"},
     "feishu": {"label": "🪽 Feishu", "default_toolset": "hermes-feishu"},
+    "wecom": {"label": "💬 WeCom", "default_toolset": "hermes-wecom"},
     "api_server": {"label": "🌐 API Server", "default_toolset": "hermes-api-server"},
     "mattermost": {"label": "💬 Mattermost", "default_toolset": "hermes-mattermost"},
 }