refactor: remove Agent preset system, fix run_command enable bug

- Delete preset-manager.ts and preset-bar.ts
- Clean up all preset references from main.ts, types.d.ts, state.ts
- Remove preset modal HTML and CSS, rename temp-slider/modal-actions classes
- Fix run_command tool not being enabled (missing setToolEnabled call)

src/renderer/state/state.ts

@@ -2,7 +2,7 @@
  * State - 轻量级响应式状态管理
  */
 
-import type { StateKey, ChatSession, ChatDB, OllamaAPI, Preset } from '../types.js';
+import type { StateKey, ChatSession, ChatDB, OllamaAPI } from '../types.js';
 
 function shallowEqual(a: unknown, b: unknown): boolean {
   if (a === b) return true;