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/features/cron.md

@@ -204,6 +204,7 @@ When scheduling jobs, you specify where the output goes:
 | `"wecom"` | WeCom | |
 | `"weixin"` | Weixin (WeChat) | |
 | `"bluebubbles"` | BlueBubbles (iMessage) | |
+| `"qqbot"` | QQ Bot (Tencent QQ) | |
 
 The agent's final response is automatically delivered. You do not need to call `send_message` in the cron prompt.