feat: 接入 LogHive 远程日志系统

- 添加 LogHiveHandler，启动时自动挂载到 root logger
- 所有 logging 日志自动异步发送到 LogHive，不影响主业务
- vendored loghive-client 包，Docker 构建时自动安装
- API Key 缺失时自动跳过，不影响本地开发

vendor/README.md

@@ -0,0 +1,84 @@
+# LogHive Client SDK
+
+Python client SDK for sending logs to [LogHive](https://github.com/your-org/loghive).
+
+## Installation
+
+```bash
+pip install loghive-client
+```
+
+Or install from source:
+
+```bash
+cd client
+pip install .
+```
+
+## Quick Start
+
+### Sync mode (recommended for scripts, Django, Flask)
+
+```python
+from loghive_client import LogHiveLogger
+
+logger = LogHiveLogger(
+    project="my-awesome-app",
+    api_key="your-api-key",
+    endpoint="http://localhost:8000",
+)
+
+logger.info("Server started", extra={"port": 8080})
+logger.error("Database timeout", exc_info=True)
+```
+
+### Async mode (for FastAPI, aiohttp, asyncio)
+
+```python
+from loghive_client import AsyncLogHiveLogger
+import asyncio
+
+async def main():
+    async with AsyncLogHiveLogger(
+        project="my-api",
+        api_key="your-api-key",
+        endpoint="http://localhost:8000",
+    ) as logger:
+        await logger.info("API started")
+        # ...
+
+asyncio.run(main())
+```
+
+### Standard logging integration (zero code change)
+
+Add the handler to your existing logger:
+
+```python
+import logging
+from loghive_client import LogHiveHandler
+
+handler = LogHiveHandler("my-project", "api-key", "http://localhost:8000")
+logging.getLogger().addHandler(handler)
+
+# All existing logger calls now forward to LogHive
+logging.info("This goes to LogHive too!")
+```
+
+## Configuration
+
+| Param | Default | Description |
+|-------|---------|-------------|
+| `project` | (required) | Your project name in LogHive |
+| `api_key` | (required) | Your project's API key |
+| `endpoint` | `http://localhost:8000` | LogHive server URL |
+| `batch_size` | 50 | Max entries per HTTP request |
+| `flush_interval` | 2.0 | Seconds between flushes |
+| `max_retries` | 3 | Retries on failure |
+| `timeout` | 5.0 | HTTP request timeout |
+
+## Trace ID (request correlation)
+
+```python
+logger.set_trace_id("req-abc-123")
+```