Replace complex behavior tracking with simpler activity monitoring

- Remove unreliable behavior-tracking.js
- Add activity-monitor.js using reliable browser APIs:
  - Visibility API for tab switch detection (actually works!)
  - Idle detection using mouse/keyboard activity
  - Focus/blur events for window tracking
  - Basic paste detection (limited by browser security)
- Simplified approach that doesn't fight browser restrictions
- Activity score calculation (0-100%)
- Cleaner UI with activity dashboard
- Works without special libraries

This approach uses only standard browser APIs that are proven to work.

Author: Archith

index.html

@@ -609,9 +609,9 @@ <h2>Sessions Management</h2>
               <span id="behavior-alert-badge" class="alert-badge" style="display: none;">0</span>
               <button id="close-notes">×</button>
             </div>
-            <!-- Behavior Monitoring Dashboard -->
-            <div id="behavior-dashboard" style="display: none; background: rgba(255,152,0,0.05); border: 1px solid rgba(255,152,0,0.2); border-radius: 4px; padding: 12px; margin: 10px;">
-              <!-- Behavior metrics will be inserted here -->
+            <!-- Activity Monitoring Dashboard -->
+            <div id="activity-dashboard" style="display: none; background: rgba(66,165,245,0.05); border: 1px solid rgba(66,165,245,0.2); border-radius: 4px; padding: 12px; margin: 10px;">
+              <!-- Activity metrics will be inserted here -->
             </div>
             <div id="notes-content">
               <div class="notes-rating-section">
@@ -716,7 +716,7 @@ <h3 class="custom-modal-title"></h3>
     <script src="/scripts/slack-integration.js?v=4"></script>
     <script src="/scripts/posthog-tracking.js?v=2"></script>
     <script src="/scripts/session-tracking.js?v=1"></script>
-    <script src="/scripts/behavior-tracking.js?v=1"></script>
+    <script src="/scripts/activity-monitor.js?v=1"></script>
     <script src="/scripts/app.js?v=3"></script>
   </body>
 </html>