Add smart activity monitoring to silence noisy programs

Automatically disable activity monitoring for constantly-updating programs:
- lazygit: Git TUI with frequent display updates
- btop: System monitor with continuous refreshing
- htop: Process monitor
- watch: Repetitive command execution
- tail: Log file following

Features:
- Auto-detection via tmux hooks (after-new-window, window-pane-changed, pane-exited)
- Re-enables monitoring when switching to normal programs
- Manual toggle with Ctrl+a A
- Eliminates false activity notifications while preserving useful ones

🤖 Generated with [Claude Code](https://claude.ai/code)

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

modules/tmux.nix

@@ -97,6 +97,28 @@
       setw -g monitor-activity on
       set -g visual-activity off
       
+      # Smart activity monitoring - disable for noisy programs
+      set-hook -g after-new-window {
+        if -F '#{||:#{||:#{||:#{||:#{==:#{pane_current_command},lazygit},#{==:#{pane_current_command},btop}},#{==:#{pane_current_command},htop}},#{==:#{pane_current_command},watch}},#{==:#{pane_current_command},tail}}' {
+          setw monitor-activity off
+        }
+      }
+      
+      set-hook -g window-pane-changed {
+        if -F '#{||:#{||:#{||:#{||:#{==:#{pane_current_command},lazygit},#{==:#{pane_current_command},btop}},#{==:#{pane_current_command},htop}},#{==:#{pane_current_command},watch}},#{==:#{pane_current_command},tail}}' {
+          setw monitor-activity off
+        } {
+          setw monitor-activity on
+        }
+      }
+      
+      set-hook -g pane-exited {
+        setw monitor-activity on
+      }
+      
+      # Manual toggle for activity monitoring
+      bind A setw monitor-activity \; display-message "Activity monitoring: #{?monitor-activity,ON,OFF}"
+      
       # Automatically renumber windows
       set -g renumber-windows on
     '';