fix: 修复平台加载和 OptionsFlow 错误

主要修复:
1. 将平台文件从 platforms/ 移到集成根目录
   - sensor.py, binary_sensor.py, switch.py, light.py, device_tracker.py
2. 修复 OptionsFlow config_entry 属性错误
   - 移除手动设置的 config_entry
3. 添加集成图标 icons/icon.png
4. manifest.json 添加 integration_type: device

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom_components/sigmesh_gateway/config_flow.py

@@ -77,10 +77,6 @@ class SigMeshGatewayConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 class SigMeshGatewayOptionsFlow(config_entries.OptionsFlow):
     """SigMesh Gateway 选项流程."""
 
-    def __init__(self, config_entry: config_entries.ConfigEntry) -> None:
-        """初始化选项流程."""
-        self.config_entry = config_entry
-
     async def async_step_init(self, user_input: dict[str, Any] | None = None) -> FlowResult:
         """管理选项."""
         if user_input is not None:

custom_components/sigmesh_gateway/manifest.json

@@ -9,5 +9,7 @@
   "requirements": ["pyserial-asyncio-fast>=0.6"],
   "config_flow": true,
   "iot_class": "local_push",
-  "loggers": ["sigmesh_gateway"]
+  "loggers": ["sigmesh_gateway"],
+  "quality_scale": "internal",
+  "integration_type": "device"
 }