Standardize response shapes and fix dead fetchT timeout keys

Three small cleanups for v1.14.0:

1. /caddy/cas now uses standard success envelope
   Was: { status: 'success', data: { cas: caList } }
   Now: { success: true, cas: caList }
   Updated frontend service-infrastructure.js to match.

2. /api/health/ca now uses standard envelope + meaningful HTTP codes
   Was: { status, message, daysUntilExpiration } with 200 on every error
   Now: { success, caStatus, message|error, daysUntilExpiration }
        with 200 / 404 / 500 as appropriate
   caStatus field preserves the original 'healthy'/'warning'/'critical'/'error'
   semantic so any future consumer of the CA-health state still has it.
   Tests updated to match.

3. Dead timeout: keys in fetchT opts are now a warning, not a silent strip
   src/utils/http.js:41 used to do  without telling
   anyone. Callers that wrote fetchT(url, { timeout: 5000 }) got the default
   5s timeout with no indication that their explicit value was ignored.
   Now it logs a warning naming the call site, then strips the key.
   Fixed 4 call sites that had stale timeout: keys:
   - src/context/caddy.js
   - src/context/dns.js
   - src/context/provider-dns.js
   - routes/dns.js (2 places)

dashcaddy-api/src/utils/http.js

@@ -38,7 +38,15 @@ function fetchT(url, opts = {}, timeoutMs = TIMEOUTS.HTTP_DEFAULT) {
   if (!opts.signal) {
     opts = { ...opts, signal: AbortSignal.timeout(timeoutMs) };
   }
-  delete opts.timeout;
+  // The `timeout` key in fetch() opts is silently ignored by undici. Callers
+  // should use the third arg of fetchT() (timeoutMs) instead. If a caller
+  // passes `timeout: N` here, it's almost certainly a bug — we used to silently
+  // strip it, which masked the issue. Now we surface it in logs and strip it.
+  if ('timeout' in opts) {
+    console.warn(`[fetchT] opts.timeout=${opts.timeout} is ignored — pass timeoutMs as the 3rd arg of fetchT() instead. Called from: ${new Error().stack.split('\n').slice(2, 4).join(' <- ')}`);
+    const { timeout, ...rest } = opts;
+    opts = rest;
+  }
   return fetch(url, opts);
 }