feat: 多租户实时切换 — 前端拦截器统一entity_id + 后端get_entity_id依赖 + dashboard 6端点支持租户过滤

- 前端: api/index.ts拦截器自动附加X-Entity-Id header + entity_id query参数
- 后端: 新增app/deps.py的get_entity_id公共依赖(query→header→默认1)
- dashboard.py: summary/kpis/finance-analysis/predict/my-kpis/my-dashboard全部支持entity_id
- 解决: 42个页面仅13个传entity_id导致切换企业后数据混乱

backend/app/deps.py

@@ -0,0 +1,26 @@
+"""多租户公共依赖 — 从请求头/参数读取当前企业ID"""
+from fastapi import Request, Header, Query, Depends
+from typing import Optional
+
+
+def get_entity_id(
+    request: Request,
+    x_entity_id: Optional[str] = Header(None, alias="X-Entity-Id"),
+    entity_id: Optional[int] = Query(None, ge=1),
+) -> int:
+    """解析当前企业ID：优先query参数 → header → 默认1(酣客)
+    前端拦截器已统一附加 X-Entity-Id header 和 entity_id query参数
+    """
+    if entity_id is not None:
+        return entity_id
+    if x_entity_id and x_entity_id.isdigit():
+        return int(x_entity_id)
+    # 兼容 body 中的 entity_id（POST场景）
+    if request.method in ("POST", "PUT", "PATCH"):
+        try:
+            body = request.state.body_json or {}
+            if body.get("entity_id"):
+                return int(body["entity_id"])
+        except Exception:
+            pass
+    return 1  # 默认酣客