docs: add QQBot to all 14 docs pages (full platform parity)

- sidebars.ts: sidebar navigation entry
- webhooks.md: deliver field routing table
- configuration.md: platform keys list
- sessions.md: platform identifiers table
- features/cron.md: delivery target table
- developer-guide/architecture.md: adapter listing
- developer-guide/cron-internals.md: delivery target table
- developer-guide/gateway-internals.md: file tree listing
- guides/cron-troubleshooting.md: supported platforms list
- integrations/index.md: platform links list
- reference/toolsets-reference.md: toolset table

(qqbot.md, environment-variables.md, and messaging/index.md were
already included in the contributor's original PR)

website/docs/developer-guide/gateway-internals.md

@@ -162,6 +162,7 @@ gateway/platforms/
 ├── wecom.py             # WeCom (WeChat Work) callback
 ├── weixin.py            # Weixin (personal WeChat) via iLink Bot API
 ├── bluebubbles.py       # Apple iMessage via BlueBubbles macOS server
+├── qqbot.py             # QQ Bot (Tencent QQ) via Official API v2
 ├── webhook.py           # Inbound/outbound webhook adapter
 ├── api_server.py        # REST API server adapter
 └── homeassistant.py     # Home Assistant conversation integration