feat: add workspace management and file preview

- Add workspace update and delete API endpoints
- Redesign selected files display to use interactive cards
- Implement VS Code-style modal for file content preview
- Enhance file tree with animations and local state
- Update UI styles for explorer, forms, and modals

lib/develop/heroprompt/heroprompt_workspace.v

@@ -431,7 +431,7 @@ fn (mut wsp Workspace) save() !&Workspace {
 }
 
 // Generate a random name for the workspace
-fn generate_random_workspace_name() string {
+pub fn generate_random_workspace_name() string {
 	adjectives := [
 		'brave',
 		'bright',