feat: Implement slash command functionality in the orchestrator

- Refactored NodePalette to remove unused templates and streamline the UI.
- Enhanced PropertyPanel to support slash commands with input fields for command name and arguments.
- Introduced TagEditor for inline variable editing and custom template creation.
- Updated PromptTemplateNode to display slash command badges and instructions.
- Modified flow types to include slashCommand and slashArgs for structured execution.
- Adjusted flow executor to construct instructions based on slash command fields.

ccw/src/core/routes/orchestrator-routes.ts

@@ -107,6 +107,16 @@ export interface PromptTemplateNodeData {
    */
   contextRefs?: string[];
 
+  /**
+   * Selected slash command name for structured execution
+   */
+  slashCommand?: string;
+
+  /**
+   * Arguments for the slash command
+   */
+  slashArgs?: string;
+
   /**
    * Error handling behavior
    */