[grade=B] DC-073: Debug request logger middleware (LOG_LEVEL=debug)

Logs method, path, status code, and duration for every request when
LOG_LEVEL=debug env var is set. Off by default in production.

All 1540 tests pass.

dashcaddy-api/src/utilities/middleware.js

@@ -571,6 +571,18 @@ module.exports = function configureMiddleware(app, {
   });
 
   app.use(generalLimiter);
+
+  // ── DC-073: Debug request logger (gated behind LOG_LEVEL=debug) ──
+  if (process.env.LOG_LEVEL === 'debug') {
+    app.use((req, res, next) => {
+      const start = Date.now();
+      res.on('finish', () => {
+        const duration = Date.now() - start;
+        process.stderr.write(`[req] ${req.method} ${req.path} ${res.statusCode} ${duration}ms\n`);
+      });
+      next();
+    });
+  }
   app.use('/api/v1/dns/credentials', strictLimiter);
   app.use('/api/v1/apps/deploy', strictLimiter);
   app.use('/api/v1/backup/restore', strictLimiter);