refactor: eliminate code duplication in cursor operations and cleanup

- Extract cursor application logic into apply_cursor_by_index() helper
- Extract cleanup logic into perform_app_cleanup() helper
- Update select_cursor(), next_cursor(), and system tray handlers to use helpers
- Reduce ~55 lines of duplicated code while maintaining functionality
- Mark step 1 of code cleanup TODO as completed

CODE_CLEANUP_TODO.md

@@ -0,0 +1,38 @@
+# Code Cleanup TODO
+
+## 🔥 Critical Issues
+
+### 1. Code Duplication
+- [x] Extract cursor application logic from `select_cursor()` and `next_cursor()`
+- [x] Extract cleanup logic from `quit_app()` and system tray quit handler
+
+### 2. Steam Integration
+- [ ] Replace `unwrap()` with proper error handling in `Steam::new()`- Leave this on the backburner for now
+- [ ] App should work fine even if Steam is offline (Steam remembers inventory, we pull from Steam even in offline mode) - Leave this on the backburner for now
+
+### 3. Unsafe Thread-Safety
+- [ ] Document or fix `SyncHCURSOR` unsafe impls in `types.rs`
+
+## 🚨 High Priority
+
+### 4. Debug Logging Spam
+- [ ] Remove 73 debug print statements from production code
+- [ ] Add proper logging framework
+
+### 5. Mutex Unwraps
+- [ ] Replace 9 `lock().unwrap()` calls with proper error handling
+
+### 6. Large Functions
+- [ ] Break down `load_cursor_files()` (90+ lines)
+- [ ] Break down `create_cursor_from_image()` (170+ lines)
+
+## 📋 Medium Priority
+
+### 7. Mock Data Fallbacks
+- [ ] Remove hardcoded fallback cursors pointing to non-existent files
+
+### 8. Inline Event Handlers
+- [ ] Extract system tray/window event handlers from Tauri builder
+
+### 9. Error Handling
+- [ ] Standardize error types and handling patterns