refactor(routes): Phase 3.4 - standardize dns.js with explicit dependencies

- Replaced god object ctx with explicit dependency injection
- Added JSDoc documenting required dependencies (7 deps vs 50+)
- Updated response calls to use response-helpers (success/error)
- Dependencies: dns, siteConfig, asyncHandler, log, safeErrorMessage, fetchT, credentialManager
- DNS record management, Technitium proxy, credential storage all preserved
- 632 lines, now self-documenting and testable

dashcaddy-api/server.js

@@ -1185,7 +1185,15 @@ Object.assign(ctx, {
 const apiRouter = express.Router();
 apiRouter.use(authRoutes(ctx));
 apiRouter.use(configRoutes(ctx));
-apiRouter.use('/dns', dnsRoutes(ctx));
+apiRouter.use('/dns', dnsRoutes({
+  dns: ctx.dns,
+  siteConfig: ctx.siteConfig,
+  asyncHandler: ctx.asyncHandler,
+  log: ctx.log,
+  safeErrorMessage: ctx.safeErrorMessage,
+  fetchT: ctx.fetchT,
+  credentialManager: ctx.credentialManager
+}));
 apiRouter.use('/notifications', notificationRoutes(ctx));
 apiRouter.use('/containers', containerRoutes({
   docker: ctx.docker,