/llm should use Inline Keyboard like ask_user does

[XMWell]

Problem

/llm outputs a plain-text model list that requires typing a number:

LLMs:
→ [0] gpt-4o
  [1] claude-sonnet-4-20250514
  [2] deepseek-v3-0324

But the ask_user flow in tgapp.py already uses InlineKeyboardMarkup — a clickable button card that's much more user-friendly on mobile.

Suggestion

Reuse _build_ask_user_markup (or a similar pattern) in cmd_llm() so model selection is one tap instead of typing a number.

Location

frontends/tgapp.py: cmd_llm() at L873-884; _build_ask_user_markup() at L288-296 already exists as a reusable helper.

[szdtzpj]

Implemented in PR #431. Telegram /llm now uses an inline keyboard for one-tap model selection.