feat(terminal): respect preferred terminal setting for Windows PTY shell

Adds Windows shell selection in the embedded PTY terminal based on
the user's preferredTerminal setting from onboarding/settings.

On Windows, the terminal preference (PowerShell, Windows Terminal, CMD)
now maps to the appropriate shell executable when spawning PTY processes.
This ensures the embedded terminal matches user expectations when they
select their preferred terminal during setup.

- Adds WINDOWS_SHELL_PATHS mapping for powershell, windowsterminal, cmd
- Implements getWindowsShell() to find first available shell executable
- Falls back to COMSPEC/cmd.exe for 'system' or unknown terminals
- Reads preferredTerminal from user settings on each spawn

apps/frontend/src/main/terminal/pty-manager.ts

@@ -5,9 +5,65 @@
 
 import * as pty from '@lydell/node-pty';
 import * as os from 'os';
+import { existsSync } from 'fs';
 import type { TerminalProcess, WindowGetter } from './types';
 import { IPC_CHANNELS } from '../../shared/constants';
 import { getClaudeProfileManager } from '../claude-profile-manager';
+import { readSettingsFile } from '../settings-utils';
+import type { SupportedTerminal } from '../../shared/types/settings';
+
+/**
+ * Windows shell paths for different terminal preferences
+ */
+const WINDOWS_SHELL_PATHS: Record<string, string[]> = {
+  powershell: [
+    'C:\\Program Files\\PowerShell\\7\\pwsh.exe',  // PowerShell 7 (Core)
+    'C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe',  // Windows PowerShell 5.1
+  ],
+  windowsterminal: [
+    'C:\\Program Files\\PowerShell\\7\\pwsh.exe',  // Prefer PowerShell Core in Windows Terminal
+    'C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe',
+  ],
+  cmd: [
+    'C:\\Windows\\System32\\cmd.exe',
+  ],
+  gitbash: [
+    'C:\\Program Files\\Git\\bin\\bash.exe',
+    'C:\\Program Files (x86)\\Git\\bin\\bash.exe',
+  ],
+  cygwin: [
+    'C:\\cygwin64\\bin\\bash.exe',
+    'C:\\cygwin\\bin\\bash.exe',
+  ],
+  msys2: [
+    'C:\\msys64\\usr\\bin\\bash.exe',
+    'C:\\msys32\\usr\\bin\\bash.exe',
+  ],
+};
+
+/**
+ * Get the Windows shell executable based on preferred terminal setting
+ */
+function getWindowsShell(preferredTerminal: SupportedTerminal | undefined): string {
+  // If no preference or 'system', use COMSPEC (usually cmd.exe)
+  if (!preferredTerminal || preferredTerminal === 'system') {
+    return process.env.COMSPEC || 'cmd.exe';
+  }
+
+  // Check if we have paths defined for this terminal type
+  const paths = WINDOWS_SHELL_PATHS[preferredTerminal];
+  if (paths) {
+    // Find the first existing shell
+    for (const shellPath of paths) {
+      if (existsSync(shellPath)) {
+        return shellPath;
+      }
+    }
+  }
+
+  // Fallback to COMSPEC for unrecognized terminals
+  return process.env.COMSPEC || 'cmd.exe';
+}
 
 /**
  * Spawn a new PTY process with appropriate shell and environment
@@ -18,13 +74,17 @@ export function spawnPtyProcess(
   rows: number,
   profileEnv?: Record<string, string>
 ): pty.IPty {
+  // Read user's preferred terminal setting
+  const settings = readSettingsFile();
+  const preferredTerminal = settings?.preferredTerminal as SupportedTerminal | undefined;
+
   const shell = process.platform === 'win32'
-    ? process.env.COMSPEC || 'cmd.exe'
+    ? getWindowsShell(preferredTerminal)
     : process.env.SHELL || '/bin/zsh';
 
   const shellArgs = process.platform === 'win32' ? [] : ['-l'];
 
-  console.warn('[PtyManager] Spawning shell:', shell, shellArgs);
+  console.warn('[PtyManager] Spawning shell:', shell, shellArgs, '(preferred:', preferredTerminal || 'system', ')');
 
   return pty.spawn(shell, shellArgs, {
     name: 'xterm-256color',