feat: Implement module permissions system with database-driven access control

- Added `users_permissions` table for managing user permissions.
- Created `PermissionRepository` for handling permission logic.
- Refactored `controls\Users::permissions()` to utilize the new database structure.
- Introduced AJAX endpoint for saving user permissions.
- Enhanced user management UI with permission checkboxes.
- Added vacation management template for handling employee absences.
- Implemented tests for `PermissionRepository`.

.serena/memories/suggested_commands.md

@@ -0,0 +1,21 @@
+# Suggested Commands
+
+## Testing
+```bash
+php tests/run.php
+```
+
+## Entry Points
+- Web: `index.php` (routes via ?module=&action=)
+- AJAX: `ajax.php`
+- REST API: `api.php`
+- Cron: `cron.php`
+
+## SCSS
+Compiled via VS Code Live Sass Compile extension (layout/style.scss -> layout/style.css)
+
+## Git
+Standard git commands (bash shell on Windows)
+
+## Utils
+Use Unix-style commands in bash shell (ls, cat, grep, find, etc.)