feat: add LOG_LEVEL env var and improve error messages

Add configurable LOG_LEVEL (fatal/error/warn/info/debug/trace) for
Fastify logger. Always return error details in tool processing
responses and combine error + details in frontend display.

apps/api/src/index.ts

@@ -34,7 +34,7 @@ await ensureDefaultAdmin();
 recoverStaleJobs();
 
 const app = Fastify({
-  logger: true,
+  logger: { level: env.LOG_LEVEL },
   bodyLimit: env.MAX_UPLOAD_SIZE_MB * 1024 * 1024,
 });
 

apps/api/src/lib/env.ts

@@ -28,6 +28,7 @@ const envSchema = z.object({
   APP_NAME: z.string().default("Stirling Image"),
   CORS_ORIGIN: z.string().default(""),
   MAX_USERS: z.coerce.number().default(5),
+  LOG_LEVEL: z.enum(["fatal", "error", "warn", "info", "debug", "trace"]).default("info"),
 });
 
 export type Env = z.infer<typeof envSchema>;

apps/api/src/routes/tool-factory.ts

@@ -306,7 +306,7 @@ export function createToolRoute<T>(app: FastifyInstance, config: ToolRouteConfig
         request.log.error({ err, toolId: config.toolId }, "Tool processing failed");
         return reply.status(422).send({
           error: "Processing failed",
-          details: process.env.NODE_ENV === "production" ? undefined : message,
+          details: message,
         });
       }
     },