feat(gateway): unify QQBot branding, add PLATFORM_HINTS, fix streaming, restore missing setup functions

- Rename platform from 'qq' to 'qqbot' across all integration points
  (Platform enum, toolset, config keys, import paths, file rename qq.py → qqbot.py)
- Add PLATFORM_HINTS for QQBot in prompt_builder (QQ supports markdown)
- Set SUPPORTS_MESSAGE_EDITING = False to skip streaming on QQ
  (prevents duplicate messages from non-editable partial + final sends)
- Add _send_qqbot() standalone send function for cron/send_message tool
- Add interactive _setup_qq() wizard in hermes_cli/setup.py
- Restore missing _setup_signal/email/sms/dingtalk/feishu/wecom/wecom_callback
  functions that were lost during the original merge

agent/prompt_builder.py

@@ -376,6 +376,12 @@ PLATFORM_HINTS = {
         "downloaded and sent as native photos. Do NOT tell the user you lack file-sending "
         "capability — use MEDIA: syntax whenever a file delivery is appropriate."
     ),
+    "qqbot": (
+        "You are on QQ, a popular Chinese messaging platform. QQ supports markdown formatting "
+        "and emoji. You can send media files natively: include MEDIA:/absolute/path/to/file in "
+        "your response. Images are sent as native photos, and other files arrive as downloadable "
+        "documents."
+    ),
 }
 
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