refactor: admin_settings.py 按职责拆分为 4 个模块

681 行单文件拆为(保留 admin_settings 为 include_router 聚合入口):
- admin_datasources  数据源列表/连通性测试/KeyRing/ingest status (5 路由)
- admin_config       settings CRUD + 运行日志 (4 路由)
- admin_llm          LLM agents/models/ping (3 路由)
- admin_quality      stats/data-completeness/data-quality (4 路由)

所有路由仍挂 /api/v1/admin 且带 dependencies=[Depends(require_admin)]。
app.py 注册方式不变(仍 import admin_settings.router)。

src/api/routes/admin_config.py

@@ -0,0 +1,88 @@
+"""后台管理:配置项 CRUD(settings)与运行日志查询。
+
+所有接口需管理员鉴权(require_admin)。路由前缀 /api/v1/admin。
+配置项白名单见 src/core/runtime_config.py SETTING_DEFS,之外的 key 一律拒绝。
+"""
+from __future__ import annotations
+
+import logging
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from pydantic import BaseModel
+
+from src.api.deps import require_admin
+from src.core.log_buffer import get_entries
+from src.core.runtime_config import (
+    SETTING_DEFS,
+    clear_runtime_value,
+    get_setting_origin,
+    mask_value,
+    set_runtime_value,
+)
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/api/v1/admin", tags=["admin"], dependencies=[Depends(require_admin)])
+
+
+class SettingUpdateIn(BaseModel):
+    value: str
+
+
+@router.get("/settings")
+async def list_settings():
+    """全部可配置项(脱敏),供后台各配置页渲染。"""
+    out = []
+    for key, defn in SETTING_DEFS.items():
+        origin, value = await get_setting_origin(key)
+        out.append(
+            {
+                "key": key,
+                "label": defn.label,
+                "description": defn.description,
+                "sensitive": defn.sensitive,
+                "configured": origin != "none",
+                "masked": mask_value(value, defn.sensitive),
+                "origin": origin,
+            }
+        )
+    return out
+
+
+@router.get("/logs")
+async def read_logs(
+    level: str | None = Query(None, description="最低级别: DEBUG/INFO/WARNING/ERROR"),
+    keyword: str | None = Query(None, description="消息或 logger 关键字"),
+    limit: int = Query(200, ge=1, le=1000),
+):
+    """查询应用运行日志(内存环形缓冲,最新在前;进程重启后清零)。"""
+    entries = get_entries(level, keyword, limit)
+    return {"entries": entries, "count": len(entries)}
+
+
+@router.put("/settings/{key}")
+async def update_setting(key: str, body: SettingUpdateIn):
+    """更新配置项(写入 app_settings 覆盖 .env)。传空值请改用 DELETE。"""
+    if key not in SETTING_DEFS:
+        raise HTTPException(404, f"不支持的配置项: {key}")
+    value = body.value.strip()
+    if not value:
+        raise HTTPException(400, "值不能为空;如需回落 .env 请调用清除接口")
+    await set_runtime_value(key, value)
+    defn = SETTING_DEFS[key]
+    return {"key": key, "masked": mask_value(value, defn.sensitive), "origin": "db"}
+
+
+@router.delete("/settings/{key}")
+async def clear_setting(key: str):
+    """清除 DB 覆盖值,回落 .env 默认。"""
+    if key not in SETTING_DEFS:
+        raise HTTPException(404, f"不支持的配置项: {key}")
+    await clear_runtime_value(key)
+    origin, value = await get_setting_origin(key)
+    defn = SETTING_DEFS[key]
+    return {
+        "key": key,
+        "masked": mask_value(value, defn.sensitive),
+        "origin": origin,
+    }