refactor(terminal): unify terminal selection using global settings

- Remove terminal selector from Session Manager page
- Backend now reads terminal preference from global settings
- Add terminal name mapping (iterm2 → iterm) for compatibility
- Add WezTerm support to macOS terminal options
- Add WezTerm translations for zh/en/ja

src/lib/api/sessions.ts

@@ -14,14 +14,12 @@ export const sessionsApi = {
   },
 
   async launchTerminal(options: {
-    target: string;
     command: string;
     cwd?: string | null;
     customConfig?: string | null;
   }): Promise<boolean> {
-    const { target, command, cwd, customConfig } = options;
+    const { command, cwd, customConfig } = options;
     return await invoke("launch_session_terminal", {
-      target,
       command,
       cwd,
       customConfig,