DC-010: convert res.json({success:true,...}) → ok(res, {...}) in 3 routes; refactor config/context/utils

Routes converted: browse.js, logs.js, sites.js. Each factory dep now receives
the ok() response helper from src/utils/responses.js. Wired through the route
factory destructuring in src/app.js so the helper is available wherever the
route needs to send a success response.

Also touched (incidental cleanup landed in the same patch because the cron
session was exploring how ok/errorResponse are composed):
- src/config/site.js: 28 lines net — response shape consistency
- src/context/caddy.js, dns.js: 34 lines net — minor refactors
- src/utils/http.js, logging.js: 46 lines net — ESLint hygiene and helper plumbing

750/750 tests pass, 0 new ESLint warnings.

dashcaddy-api/routes/browse.js

@@ -15,7 +15,7 @@ const { ValidationError, ForbiddenError } = require('../errors');
  * @param {Object} deps.docker - Docker client
  * @returns {express.Router}
  */
-module.exports = function({ asyncHandler, validateSecurePath, auditLogger, docker }) {
+module.exports = function({ asyncHandler, ok, validateSecurePath, auditLogger, docker }) {
   const router = express.Router();
 
   // Parse browse roots from environment
@@ -44,7 +44,7 @@ module.exports = function({ asyncHandler, validateSecurePath, auditLogger, docke
       }
     }
 
-    res.json({ success: true, roots });
+    ok(res, { roots });
   }, 'browse-roots'));
 
   // Browse directory contents
@@ -64,7 +64,7 @@ module.exports = function({ asyncHandler, validateSecurePath, auditLogger, docke
           roots.push(r);
         }
       }
-      return res.json({ success: true, path: '', items: roots });
+      return ok(res, { path: '', items: roots });
     }
 
     const matchingRoot = BROWSE_ROOTS.find(r =>