fix: Remove persistent floating update notification

- Completely removed floating notification element from DOM
- Fixed issue where notification would not disappear
- Added aggressive cleanup of localStorage to prevent state persistence
- Implemented DOM observer to prevent notification reappearance
- Simplified update alert system to use dashboard-only notifications
- Updated version to 2.0.12

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

public/index.html

@@ -733,15 +733,8 @@
         }
     </style>
     
-    <!-- Floating update notification (outside normal document flow) -->
-    <div id="floating-update-notification">
-        <div>Update Available!</div>
-        <div id="floating-update-version">New version available</div>
-        <div class="button-container">
-            <button id="floating-update-button">Update Now</button>
-            <button id="floating-refresh-button" style="background-color: #4CAF50; margin-left: 10px;">Refresh Status</button>
-        </div>
-    </div>
+    <!-- Removed floating notification completely -->
+    <!-- The floating notification was removed to fix persistent display issues -->
     
     <!-- JavaScript Files -->
     <script src="/js/system-status.js"></script>