feat(gateway): 全局串行化(并发=1) + 记录入参/出参/耗时日志

并发模型从「每worker并发1 + 多worker并行」改为全局串行：同一时间
只处理1个请求，其余排队；多 worker 仅作热备（主 worker 坏了才用备机）。
接口4(face/features) 走豆包、不占 GPU，不纳入串行。

- pool: asyncio.Semaphore(max_global_concurrency=1) + acquire/release_global_slot
  （依赖单进程 uvicorn 部署，已在注释中标注）
- forward: proxy_request 最外层 acquire 全局槽、try/finally 全路径释放；
  入参 multipart 解析挂 request.state；原重试/故障转移逻辑抽到 _dispatch_with_retries
- reqlog(新): 标量入参保留；图片(file/base64)存盘转URL，绝不内嵌base64；
  出参递归摘要截断(landmarks/长串/大数组)
- logging_middleware: RequestLogEntry 加 request_params/response_data，
  jsonl 全量记录；_load_from_logfile 同步映射防重启丢字段；get_stats recent 暴露
- /gateway-health 暴露 global_max/global_busy/global_waiting
- config: dispatch 新增 max_global_concurrency / max_queue_wait_seconds
- tests: test_reqlog + test_gateway_serialization（9 用例）

顺带提交此前未提交的网关统计(daily stats 接口)与耗时看板(api_timing_dashboard.html)。

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

tests/test_gateway_serialization.py

@@ -0,0 +1,58 @@
+"""gateway.pool 全局串行槽单测：验证 max_global_concurrency=1 时同一时间只跑1个请求、
+排队超时返回 False。
+
+用 asyncio.run 套同步测试，避免引入 pytest-asyncio 依赖。
+"""
+
+import asyncio
+
+from gateway import pool
+
+_CFG = {"dispatch": {"max_global_concurrency": 1, "max_queue_wait_seconds": 590}}
+_CFG_FAST_TIMEOUT = {"dispatch": {"max_global_concurrency": 1, "max_queue_wait_seconds": 0.2}}
+
+
+def test_global_slot_serializes_to_one():
+    pool.init_global_slot(_CFG)
+
+    state = {"active": 0, "peak": 0}
+
+    async def task():
+        got = await pool.acquire_global_slot(_CFG)
+        assert got is True
+        state["active"] += 1
+        state["peak"] = max(state["peak"], state["active"])
+        await asyncio.sleep(0.03)
+        state["active"] -= 1
+        pool.release_global_slot()
+
+    async def run():
+        await asyncio.gather(*(task() for _ in range(4)))
+
+    asyncio.run(run())
+    assert state["peak"] == 1, f"期望峰值并发=1，实际={state['peak']}"
+    assert pool.get_pool_status()["global_busy"] == 0
+
+
+def test_global_slot_timeout_returns_false():
+    pool.init_global_slot(_CFG_FAST_TIMEOUT)
+
+    async def run():
+        first = await pool.acquire_global_slot(_CFG_FAST_TIMEOUT)
+        assert first is True
+        # 槽已被占用，第二个应在 0.2s 内超时
+        second = await pool.acquire_global_slot(_CFG_FAST_TIMEOUT)
+        assert second is False
+        pool.release_global_slot()
+
+    asyncio.run(run())
+    assert pool.get_pool_status()["global_busy"] == 0
+
+
+def test_get_pool_status_has_global_fields():
+    pool.init_global_slot(_CFG)
+    status = pool.get_pool_status()
+    assert "global_max" in status
+    assert "global_busy" in status
+    assert "global_waiting" in status
+    assert status["global_max"] == 1