feat: comprehensive test infrastructure improvements

- Fix unit test imports: add env setup in conftest.py before module imports
- Add 24 new auth router tests (RBAC, preferences, password validation)
- Add 16 new tests for litellm and chat_summary routers
- Apply black formatting and ruff linting across codebase
- Add pre-commit hooks configuration (black, ruff, file checks)
- Increase CI coverage threshold from 40% to 50%

Test Results:
- 206 tests passing (91 unit + 115 integration)
- Coverage: 58.79% on core modules
- auth.py: 57% → 85%, litellm.py: 23% → 87%, chat_summary.py: 41% → 100%
- auth_service: 96.51%, config: 100%, rbac: 93.48%

dashboard/backend/routers/opc_agents.py

@@ -1,25 +1,26 @@
 """
 OPC Agents Router
 """
+
 from fastapi import APIRouter, Depends, HTTPException, Request
-from typing import Optional, List
 from pydantic import BaseModel
+
 from db import opc_db
-from rbac import require_page, User, require_admin
+from rbac import User, require_admin
 
 router = APIRouter()
 
 
 class AgentUpdate(BaseModel):
-    name: Optional[str] = None
-    description: Optional[str] = None
-    system_prompt: Optional[str] = None
-    enabled: Optional[bool] = None
+    name: str | None = None
+    description: str | None = None
+    system_prompt: str | None = None
+    enabled: bool | None = None
 
 
 class ExecutionApproval(BaseModel):
     approved: bool
-    feedback: Optional[str] = None
+    feedback: str | None = None
 
 
 @router.get("/agents")
@@ -60,7 +61,7 @@ async def update_agent(
             name=updates.name,
             description=updates.description,
             system_prompt=updates.system_prompt,
-            enabled=updates.enabled
+            enabled=updates.enabled,
         )
         return agent
     except ValueError as e:
@@ -75,30 +76,21 @@ async def trigger_agent(
 ):
     """Manually trigger agent execution"""
     user: User = request.state.user
-    execution = await opc_db.create_agent_execution(
-        task_id=task_id,
-        agent_id=agent_id,
-        actor=user.username
-    )
+    execution = await opc_db.create_agent_execution(task_id=task_id, agent_id=agent_id, actor=user.username)
     return execution
 
 
 @router.get("/executions")
 async def list_executions(
     request: Request,
-    task_id: Optional[int] = None,
-    agent_id: Optional[str] = None,
-    status: Optional[str] = None,
+    task_id: int | None = None,
+    agent_id: str | None = None,
+    status: str | None = None,
     limit: int = 50,
 ):
     """List agent executions"""
     user: User = request.state.user
-    executions = await opc_db.get_agent_executions(
-        task_id=task_id,
-        agent_id=agent_id,
-        status=status,
-        limit=limit
-    )
+    executions = await opc_db.get_agent_executions(task_id=task_id, agent_id=agent_id, status=status, limit=limit)
     return {"items": executions}
 
 
@@ -125,10 +117,7 @@ async def approve_execution(
     user: User = request.state.user
     try:
         execution = await opc_db.approve_agent_execution(
-            execution_id=execution_id,
-            approved=approval.approved,
-            approved_by=user.username,
-            feedback=approval.feedback
+            execution_id=execution_id, approved=approval.approved, approved_by=user.username, feedback=approval.feedback
         )
         return execution
     except ValueError as e: