feat: enhance project-specific slash commands management

- Add scopeFilter prop to SlashCommandsManager for filtering by scope
- Replace browser confirm() with proper delete confirmation dialog
- Fix slash_command_delete to handle project commands with project_path param
- Add Slash Commands tab to ProjectSettings as the default tab
- Add Commands button to ClaudeCodeSession for quick access
- Improve error handling and user feedback for delete operations
- Better UI text when showing project-specific commands only

src/lib/api.ts

@@ -1825,11 +1825,12 @@ export const api = {
   /**
    * Deletes a slash command
    * @param commandId - Unique identifier of the command to delete
+   * @param projectPath - Optional project path for deleting project commands
    * @returns Promise resolving to deletion message
    */
-  async slashCommandDelete(commandId: string): Promise<string> {
+  async slashCommandDelete(commandId: string, projectPath?: string): Promise<string> {
     try {
-      return await invoke<string>("slash_command_delete", { commandId });
+      return await invoke<string>("slash_command_delete", { commandId, projectPath });
     } catch (error) {
       console.error("Failed to delete slash command:", error);
       throw error;