feat(telegram): generic inline keyboard buttons for gateway commands

[rahimsais]

Summary

Add a reusable inline keyboard button system for Telegram gateway commands, complementing the existing model picker (#5742).

Architecture

• BasePlatformAdapter.send_inline_options() — generic method with text fallback for non-Telegram platforms
• TelegramAdapter override renders native InlineKeyboardButton
• Generic callback routing: cmd:args → synthetic /cmd args through _message_handler
• Dedicated cpg: callback prefix for /commands pagination (edit-in-place, like model picker's mp:/mg:)
• mc cancel callback as standard UX pattern
• gateway_runner reference set on all adapters during init for cross-reference

Commands with inline buttons

Command	Behavior
/commands	Paginated Prev/Next that edits in-place (like model picker)
/personality	Picker with all configured personalities
/rollback	Checkpoint list picker
/resume	Named session picker
Dangerous commands	Approval buttons: Allow Once / Allow Session / Always Allow / Deny

Fixes included

• Drop ParseMode.MARKDOWN from callback message edits — skill descriptions with unbalanced backticks break Telegram's markdown parser
• Truncate skill descriptions to 120 chars in /commands pages to stay under Telegram's 4096 char limit
• Use getattr for dynamically-set gateway_runner attribute

Files changed

• gateway/platforms/base.py — send_inline_options() base method
• gateway/platforms/telegram.py — native inline keyboard + callback handlers
• gateway/run.py — extracted _build_commands_page() helper, inline buttons for 4 commands, gateway_runner init on all adapters

[teknium1]

The approval button functionality was merged in #5890 (approval buttons for Slack & Telegram + callback handling). The generic inline button system for other commands (/commands, /personality, etc.) is an interesting idea but would need a full rebase and removal of the now-redundant approval parts. Closing as substantially superseded — if you'd like to resubmit just the generic button system as a separate PR, that would be welcome.