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/user-guide/sessions.md

@@ -46,6 +46,7 @@ Each session is tagged with its source platform:
 | `wecom` | WeCom (WeChat Work) |
 | `weixin` | Weixin (personal WeChat) |
 | `bluebubbles` | Apple iMessage via BlueBubbles macOS server |
+| `qqbot` | QQ Bot (Tencent QQ) via Official API v2 |
 | `homeassistant` | Home Assistant conversation |
 | `webhook` | Incoming webhooks |
 | `api-server` | API server requests |