feat: improve Pro feature UI gating and error handling

- AISettings: Add Pro badge & disabled state for Autonomous Mode toggle
- APIClient: Parse JSON error responses for better user-facing messages
- Supports new 402 Payment Required responses from license-gated endpoints

frontend-modern/src/components/Settings/AISettings.tsx

@@ -1177,17 +1177,33 @@ export const AISettings: Component = () => {
                           ENABLED
                         </span>
                       </Show>
+                      <Show when={autoFixLocked()}>
+                        <span class="px-1.5 py-0.5 text-[10px] font-semibold bg-amber-100 dark:bg-amber-900 text-amber-700 dark:text-amber-300 rounded">Pro</span>
+                      </Show>
                     </label>
                     <p class="text-xs text-gray-600 dark:text-gray-400 mt-1">
                       {form.autonomousMode
                         ? 'AI will execute all commands without asking for approval. Only enable if you trust your configured model.'
                         : 'AI will ask for approval before running commands that modify your system. Read-only commands (like df, ps, docker stats) run automatically.'}
                     </p>
+                    <Show when={autoFixLocked()}>
+                      <p class="text-[10px] text-amber-600 dark:text-amber-400 mt-1">
+                        Pulse Pro required for autonomous mode.{' '}
+                        <a
+                          class="underline decoration-dotted"
+                          href="https://pulserelay.pro"
+                          target="_blank"
+                          rel="noreferrer"
+                        >
+                          Upgrade
+                        </a>
+                      </p>
+                    </Show>
                   </div>
                   <Toggle
                     checked={form.autonomousMode}
                     onChange={(event) => setForm('autonomousMode', event.currentTarget.checked)}
-                    disabled={saving()}
+                    disabled={saving() || autoFixLocked()}
                   />
                 </div>
               </div>

frontend-modern/src/utils/apiClient.ts

@@ -325,18 +325,31 @@ class ApiClient {
       // Try to extract just the error message without HTTP status codes
       let errorMessage = text;
 
-      // If it looks like an HTML error page, try to extract the message
-      if (text.includes('<pre>') && text.includes('</pre>')) {
-        const match = text.match(/<pre>(.*?)<\/pre>/s);
-        if (match) errorMessage = match[1];
-      }
+      // First try to parse as JSON (our API returns structured errors like {error, message, feature, upgrade_url})
+      try {
+        const jsonError = JSON.parse(text);
+        if (jsonError.message) {
+          errorMessage = jsonError.message;
+        } else if (jsonError.error && typeof jsonError.error === 'string') {
+          // Some APIs return {error: "message"} format
+          errorMessage = jsonError.error;
+        }
+      } catch {
+        // Not JSON, try other formats
 
-      // If the backend sent a plain text error, use it directly
-      if (!text.includes('<') && text.length < 200) {
-        errorMessage = text;
-      } else if (text.length > 200) {
-        // For long responses, just use a generic message
-        errorMessage = `Request failed with status ${response.status}`;
+        // If it looks like an HTML error page, try to extract the message
+        if (text.includes('<pre>') && text.includes('</pre>')) {
+          const match = text.match(/<pre>(.*?)<\/pre>/s);
+          if (match) errorMessage = match[1];
+        }
+
+        // If the backend sent a plain text error, use it directly
+        if (!text.includes('<') && text.length < 200) {
+          errorMessage = text;
+        } else if (text.length > 200) {
+          // For long responses, just use a generic message
+          errorMessage = `Request failed with status ${response.status}`;
+        }
       }
 
       throw new Error(errorMessage || `Request failed with status ${response.status}`);