fix(js): resolve Biome lint warnings across 9 JS files

noUnusedVariables (catch bindings → optional catch syntax):
- app.js, file-upload.js, timezone-selector.js: } catch (e) { → } catch {
  ES2019 optional catch binding; e was unused in all three handlers

noUnusedVariables (dead assignments):
- app.js: remove const data= in display SSE stub (handler does nothing yet)
- api_client.js: remove const timeoutId= (setTimeout ID never used to cancel)
- custom-feeds.js: remove const oldIndex= (getAttribute result never read)
- schedule-picker.js: remove const compactMode= (never used in HTML build)
- select-dropdown.js: remove const icons= (icons not yet rendered in options)

noPrototypeBuiltins:
- day-selector.js: DAY_LABELS.hasOwnProperty(x) →
  Object.prototype.hasOwnProperty.call(DAY_LABELS, x)
  Safe form that works even on null-prototype objects

useIterableCallbackReturn:
- file-upload.js, notification.js: forEach(x => expr) →
  forEach(x => { expr; }) — forEach ignores return values;
  implicit return from arrow body was misleading

htmx-sse.js is a vendor extension file with old-style var/== patterns
that are correct for it; 18 Biome issues suppressed via Codacy API
rather than modifying the vendor source.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web_interface/static/v3/app.js

@@ -45,7 +45,7 @@ document.body.addEventListener('htmx:afterRequest', function(event) {
             if (data.message) {
                 showNotification(data.message, data.status || 'info');
             }
-        } catch (e) {
+        } catch {
             // Not JSON, ignore
         }
     }
@@ -65,8 +65,7 @@ window.reconnectSSE = function() {
     if (window.displaySource) {
         window.displaySource.close();
         window.displaySource = new EventSource('/api/v3/stream/display');
-        window.displaySource.onmessage = function(event) {
-            const data = JSON.parse(event.data);
+        window.displaySource.onmessage = function() {
             // Handle display updates
         };
     }

web_interface/static/v3/js/plugins/api_client.js

@@ -40,7 +40,7 @@ const RequestThrottler = {
         // Create throttled request with abort support
         let abortController = null;
         const promise = new Promise((resolve, reject) => {
-            const timeoutId = setTimeout(async () => {
+            setTimeout(async () => {
                 try {
                     const result = await fn();
                     // Cache successful GET requests

web_interface/static/v3/js/widgets/custom-feeds.js

@@ -364,7 +364,6 @@
             // Re-index remaining rows
             const rows = tbody.querySelectorAll('.custom-feed-row');
             rows.forEach((r, index) => {
-                const oldIndex = r.getAttribute('data-index');
                 r.setAttribute('data-index', index);
                 // Update all input names with new index
                 r.querySelectorAll('input, button').forEach(input => {

web_interface/static/v3/js/widgets/day-selector.js

@@ -91,7 +91,7 @@
             const xOptions = config['x-options'] || config['x_options'] || {};
             const requestedFormat = xOptions.format || 'long';
             // Validate format exists in DAY_LABELS, default to 'long' if not
-            const format = DAY_LABELS.hasOwnProperty(requestedFormat) ? requestedFormat : 'long';
+            const format = Object.prototype.hasOwnProperty.call(DAY_LABELS, requestedFormat) ? requestedFormat : 'long';
             const layout = xOptions.layout || 'horizontal';
             const showSelectAll = xOptions.selectAll !== false;
 

web_interface/static/v3/js/widgets/file-upload.js

@@ -294,7 +294,7 @@
         if (fileType !== 'json') {
             formData.append('plugin_id', pluginId);
         }
-        validFiles.forEach(file => formData.append('files', file));
+        validFiles.forEach(file => { formData.append('files', file); });
         
         try {
             const response = await fetch(customUploadEndpoint, {
@@ -741,7 +741,7 @@
         try {
             const date = new Date(dateString);
             return date.toLocaleDateString() + ' ' + date.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
-        } catch (e) {
+        } catch {
             return dateString;
         }
     };

web_interface/static/v3/js/widgets/notification.js

@@ -199,7 +199,7 @@
      */
     function clearAll() {
         const ids = [...activeNotifications];
-        ids.forEach(id => removeNotification(id, true));
+        ids.forEach(id => { removeNotification(id, true); });
     }
 
     // Register the widget

web_interface/static/v3/js/widgets/schedule-picker.js

@@ -174,7 +174,6 @@
             const xOptions = config['x-options'] || config['x_options'] || {};
             const showModeToggle = xOptions.showModeToggle !== false;
             const showEnableToggle = xOptions.showEnableToggle !== false;
-            const compactMode = xOptions.compactMode === true;
 
             const schedule = normalizeSchedule(value);
 

web_interface/static/v3/js/widgets/select-dropdown.js

@@ -69,7 +69,6 @@
             const enumValues = config.enum || xOptions.options || [];
             const placeholder = xOptions.placeholder || 'Select...';
             const labels = xOptions.labels || {};
-            const icons = xOptions.icons || {};
             const disabled = xOptions.disabled === true;
             const required = xOptions.required === true;
 

web_interface/static/v3/js/widgets/timezone-selector.js

@@ -358,7 +358,7 @@
                     });
                     timeEl.textContent = formatter.format(now);
                     previewEl.classList.remove('hidden');
-                } catch (e) {
+                } catch {
                     previewEl.classList.add('hidden');
                 }
             }