feat(web): plugin install auto-enables + persistent restart nudge

Getting a plugin onto the display used to take three disconnected manual
steps: install from the store, flip its enable toggle, then restart the
display service - with no in-UI hint that steps 2 and 3 were needed (only
docs/GETTING_STARTED.md mentions it).

- installPlugin() now enables the plugin immediately on successful install
  (owner-confirmed behavior change: always auto-enable, no opt-out; users
  who don't want it running toggle it off as before), then shows a
  persistent toast ("... restart the display to show it") with an inline
  "Restart Now" button wired to the existing restartDisplay() - the same
  function the three existing Restart Display buttons call.
- notification.js: show() accepts optional { actionLabel, onAction } to
  render one inline action button per toast. Callbacks are stored per
  notification id and cleaned up on dismiss; a new triggerAction() public
  method runs the callback and dismisses. The global showNotification()
  shorthand now forwards a full options object as its second argument
  (legacy type-string calls unchanged).

Scope note: applies to the plugin store's install path (window.installPlugin).
The custom-registry install path keeps its existing behavior.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEZK1P1Q1fu5pcuVrkrCFZ

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

@@ -58,6 +58,9 @@
 
     // Track active notifications
     let activeNotifications = [];
+    // onAction callbacks for notifications with an inline action button,
+    // keyed by notification id (cleaned up on dismiss).
+    const actionCallbacks = {};
     let notificationCounter = 0;
 
     /**
@@ -113,6 +116,7 @@
 
         // Remove from tracking array
         activeNotifications = activeNotifications.filter(id => id !== notificationId);
+        delete actionCallbacks[notificationId];
     }
 
     /**
@@ -158,6 +162,20 @@
 
         html += `<span class="flex-1 text-sm">${escapeHtml(message)}</span>`;
 
+        // Optional inline action button (e.g. "Restart Now" on a restart nudge).
+        // The callback is stored by id and invoked via triggerAction, which
+        // also dismisses the notification.
+        if (options.actionLabel && typeof options.onAction === 'function') {
+            actionCallbacks[notificationId] = options.onAction;
+            html += `
+                <button type="button"
+                        onclick="window.LEDMatrixWidgets.get('notification').triggerAction('${notificationId}')"
+                        class="flex-shrink-0 ml-2 px-3 py-1 text-xs font-semibold rounded-md bg-white bg-opacity-20 hover:bg-opacity-30 transition-colors duration-150">
+                    ${escapeHtml(options.actionLabel)}
+                </button>
+            `;
+        }
+
         if (dismissible) {
             html += `
                 <button type="button"
@@ -227,6 +245,17 @@
             removeNotification(notificationId);
         },
 
+        /**
+         * Invoke a notification's onAction callback (see options.actionLabel /
+         * options.onAction on show) and dismiss it.
+         * @param {string} notificationId - Notification ID whose action to run
+         */
+        triggerAction: function(notificationId) {
+            const cb = actionCallbacks[notificationId];
+            removeNotification(notificationId);
+            if (cb) cb();
+        },
+
         /**
          * Clear all notifications
          */
@@ -262,9 +291,11 @@
         }
     });
 
-    // Global shorthand function (backwards compatible with existing code)
+    // Global shorthand function (backwards compatible with existing code).
+    // Accepts either the legacy type string or a full options object
+    // ({ type, duration, actionLabel, onAction, ... }).
     window.showNotification = function(message, type = 'info') {
-        return showNotification(message, { type: type });
+        return showNotification(message, typeof type === 'string' ? { type: type } : (type || {}));
     };
 
     // Initialize container on load