Numpad keys not working in TUI prompt and dialogs #20461

Problem

Numpad keys (0-9, Enter, operators, navigation) are not recognized in the TUI. This affects:

1. Numpad Enter (kpenter) does not submit the prompt, confirm dialogs, or select options — only the main keyboard return key works.
2. Numpad digits (0-9) are not inserted into the prompt input when using terminals that use the kitty keyboard protocol.
3. Numpad navigation (Home, End, arrow keys via numpad) does not move the cursor in the input field.

Root Cause

The TUI keybinding system only recognizes return as the Enter key and does not account for numpad-specific key names from the kitty keyboard protocol (kpenter, kpequal, kp0-kp9, etc.) or legacy SS3 escape sequences.

Changes

• keybind.ts: Add isEnterKey() helper that accepts return, kpenter, and kpequal. Add detectNumpadKeyName() in Keybind.fromParsedKey() to detect numpad keys from kitty protocol names, legacy SS3 sequences, and modifyOtherKeys CSI-u codes.
• config.ts: Add numpad key equivalents to all input keybinding defaults (kpenter/kpequal for submit, kp0-kp9 for digits, kp4/kp6/kp8/kp2 for arrows, kp7/kp9/kphome/kpend for Home/End, etc.).
• prompt/index.tsx: Add handlers for kp0-kp9 and numpad operators (/, *, -, +, ., =) to insert the corresponding characters.
• Dialogs: Replace all evt.name === "return" checks with isEnterKey(evt) across dialog-alert, dialog-confirm, dialog-export-options, dialog-help, dialog-prompt, dialog-select, permission.tsx, question.tsx, and autocomplete.tsx.

Affected Components

• TUI prompt input
• All dialogs (alert, confirm, prompt, select, help, export-options)
• Permission prompts
• Question prompts
• Autocomplete

Environment

Windows terminals using kitty keyboard protocol and terminals that send legacy SS3 sequences for numpad keys.