feat: add QQ Bot platform adapter (Official API v2)

Add full QQ Bot integration via the Official QQ Bot API (v2):
- WebSocket gateway for inbound events (C2C, group, guild, DM)
- REST API for outbound text/markdown/media messages
- Voice transcription (Tencent ASR + configurable STT provider)
- Attachment processing (images, voice, files)
- User authorization (allowlist + allow-all + DM pairing)

Integration points:
- gateway: Platform.QQ enum, adapter factory, allowlist maps
- CLI: setup wizard, gateway config, status display, tools config
- tools: send_message cross-platform routing, toolsets
- cron: delivery platform support
- docs: QQ Bot setup guide

gateway/config.py

@@ -66,6 +66,7 @@ class Platform(Enum):
     WECOM_CALLBACK = "wecom_callback"
     WEIXIN = "weixin"
     BLUEBUBBLES = "bluebubbles"
+    QQ = "qq"
 
 
 @dataclass
@@ -303,6 +304,9 @@ class GatewayConfig:
             # BlueBubbles uses extra dict for local server config
             elif platform == Platform.BLUEBUBBLES and config.extra.get("server_url") and config.extra.get("password"):
                 connected.append(platform)
+            # QQ uses extra dict for app credentials
+            elif platform == Platform.QQ and config.extra.get("app_id") and config.extra.get("client_secret"):
+                connected.append(platform)
         return connected
     
     def get_home_channel(self, platform: Platform) -> Optional[HomeChannel]:
@@ -1109,6 +1113,32 @@ def _apply_env_overrides(config: GatewayConfig) -> None:
             name=os.getenv("BLUEBUBBLES_HOME_CHANNEL_NAME", "Home"),
         )
 
+    # QQ (Official Bot API v2)
+    qq_app_id = os.getenv("QQ_APP_ID")
+    qq_client_secret = os.getenv("QQ_CLIENT_SECRET")
+    if qq_app_id or qq_client_secret:
+        if Platform.QQ not in config.platforms:
+            config.platforms[Platform.QQ] = PlatformConfig()
+        config.platforms[Platform.QQ].enabled = True
+        extra = config.platforms[Platform.QQ].extra
+        if qq_app_id:
+            extra["app_id"] = qq_app_id
+        if qq_client_secret:
+            extra["client_secret"] = qq_client_secret
+        qq_allowed_users = os.getenv("QQ_ALLOWED_USERS", "").strip()
+        if qq_allowed_users:
+            extra["allow_from"] = qq_allowed_users
+        qq_group_allowed = os.getenv("QQ_GROUP_ALLOWED_USERS", "").strip()
+        if qq_group_allowed:
+            extra["group_allow_from"] = qq_group_allowed
+        qq_home = os.getenv("QQ_HOME_CHANNEL", "").strip()
+        if qq_home:
+            config.platforms[Platform.QQ].home_channel = HomeChannel(
+                platform=Platform.QQ,
+                chat_id=qq_home,
+                name=os.getenv("QQ_HOME_CHANNEL_NAME", "Home"),
+            )
+
     # Session settings
     idle_minutes = os.getenv("SESSION_IDLE_MINUTES")
     if idle_minutes: