[grade=A] DC-065: Sweep 15 console.* calls to process.stderr.write

Replace all non-logger console.error/warn calls with process.stderr.write
using tagged prefixes ([AuditLogger], [CSRF], [DNS Registry], etc.) for
grep-ability. All in fallback/catch paths where structured logger may be
unavailable. Test updated to use jest.spyOn with try/finally for clean
mock restoration.

Codex grade: pass (22,402 tokens). All 1539 tests pass.

dashcaddy-api/src/utilities/error-handler.js

@@ -34,7 +34,7 @@ function errorMiddleware(err, req, res, next) {
       userId: req.user?.id,
       body: req.body
     }
-  ).catch(e => console.error('Failed to write to error log:', e.message));
+  ).catch(e => process.stderr.write(`[error-handler] Failed to write to error log: ${e.message}\n`));
 
   // Determine if this is an operational error (AppError) or programming error
   const isOperational = err.isOperational || err instanceof AppError;
@@ -65,11 +65,7 @@ function errorMiddleware(err, req, res, next) {
 
   // For non-operational errors, log as fatal
   if (!isOperational) {
-    console.error('FATAL: Non-operational error detected', {
-      error: err.message,
-      stack: err.stack,
-      path: req.path
-    });
+    process.stderr.write(`[FATAL] Non-operational error detected: ${JSON.stringify({ error: err.message, stack: err.stack, path: req.path })}\n`);
   }
 }