Phase 3: Fix medium-priority issues (M1-M4, M6)

M1: Password complexity validation (min 8 chars, uppercase, lowercase, digit)
M2: Remove is_system_admin from login response (prevent role leaking)
M3: Permission cache invalidates on DB error instead of using stale data
M4: .env.docker.example already fixed in B9 (SECRET_KEY, FRONTEND_URL, SMTP)
M6: Frontend test setup auto-wraps with QueryClientProvider (fixes ~29 test failures)

Remaining: M5 (frontend component integration — WelcomeDialog, SavedFilterBar, etc.)

app/schemas/auth.py

@@ -2,7 +2,8 @@
 
 from __future__ import annotations
 
-from pydantic import BaseModel, EmailStr, Field
+from pydantic import BaseModel, EmailStr, Field, field_validator
+from app.schemas.user import _validate_password_complexity
 
 
 class LoginRequest(BaseModel):
@@ -19,6 +20,11 @@ class PasswordResetConfirm(BaseModel):
     token: str = Field(..., min_length=1)
     new_password: str = Field(..., min_length=8)
 
+    @field_validator("new_password")
+    @classmethod
+    def validate_password(cls, v: str) -> str:
+        return _validate_password_complexity(v)
+
 
 class SwitchTenantRequest(BaseModel):
     tenant_id: str = Field(..., min_length=1)