feat(backend): add error handling schemas for validation and internal server errors

Author: Lasim

services/backend/src/routes/cloud-credentials/schemas.ts

@@ -337,6 +337,12 @@ export const searchCredentialsSchema = {
       data: z.array(SearchCredentialsResponseSchema).describe('Array of matching credentials (metadata only, no secret values)')
     }).describe('Search completed successfully'), { 
       }),
+    400: createSchema(z.object({
+      success: z.boolean().default(false).describe('Indicates if the operation was successful (false for errors)'),
+      error: z.string().describe('Error message'),
+      details: z.array(z.string()).describe('Validation error details').optional()
+    }).describe('Bad Request - Validation error'), { 
+      }),
     401: createSchema(z.object({
       success: z.boolean().default(false).describe('Indicates if the operation was successful (false for errors)'),
       error: z.string().describe('Error message')

services/backend/src/routes/gateway/config/list-clients.ts

@@ -36,6 +36,10 @@ export default async function listClients(server: FastifyInstance) {
         403: {
           ...ERROR_RESPONSE_SCHEMA,
           description: 'Forbidden - Insufficient permissions'
+        },
+        500: {
+          ...ERROR_RESPONSE_SCHEMA,
+          description: 'Internal Server Error'
         }
       }
     }

services/backend/src/routes/mcp/github/get-repo-info.ts

@@ -108,6 +108,13 @@ export default async function getRepoInfo(server: FastifyInstance) {
             success: { type: 'boolean', default: false },
             error: { type: 'string' }
           }
+        },
+        500: {
+          type: 'object',
+          properties: {
+            success: { type: 'boolean', default: false },
+            error: { type: 'string' }
+          }
         }
       }
     }