Fix enter key mapping for proper command execution

- Change enter key from '\r' to '\n' for correct shell behavior
- Swap enter and ctrl_enter mappings to match terminal expectations
- Most shells expect newline (\n) to execute commands, not carriage return (\r)

This fixes the issue where commands typed in frontend would hang
after pressing enter instead of executing properly.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

web/src/pty/PtyManager.ts

@@ -394,8 +394,8 @@ export class PtyManager {
       arrow_right: '\x1b[C',
       arrow_left: '\x1b[D',
       escape: '\x1b',
-      enter: '\r',
-      ctrl_enter: '\n',
+      enter: '\n',
+      ctrl_enter: '\r',
       shift_enter: '\r\n',
     };