feat: Phase 3 - AES encryption, SQL audit engine, audit logs (85 tests)

Phase 3.1: Instance password AES-256-GCM encryption
Phase 3.2: SQL audit rule engine (10 rules)
Phase 3.3: Auto-audit on ticket creation
Phase 3.4: Operation audit logs + GET /audit/logs
Tests: 44 -> 85 (41 new), Frontend: AuditLogsPage

backend/app/api/v1/endpoints/query.py

@@ -9,6 +9,7 @@ from app.models.instance import Instance
 from app.models.audit_log import AuditLog
 from app.schemas.query import QueryRequest, QueryResult
 from app.services.query_service import QueryService
+from app.core.crypto import decrypt_password
 
 router = APIRouter(prefix="/query", tags=["SQL 查询"])
 
@@ -27,6 +28,9 @@ async def execute_query(
     if not instance:
         raise HTTPException(status_code=404, detail="数据源不存在")
 
+    # Decrypt password for query execution
+    instance.password = decrypt_password(instance.password)
+
     try:
         query_result = await QueryService.execute_query(instance, req.database, req.sql, current_user.id)
     except ValueError as e: