Add number key shortcuts for agent prompts

[boudra]

Summary

• add rebindable 1/2/3 prompt-selection shortcuts to the shared keyboard shortcuts system
• scope those shortcuts to agents that are actively awaiting user input and route them through the focused agent pane
• support sequential question-card selection with keyboard hints and add regression coverage for the shortcut matcher and question selection state

Verification

• npm test --workspace=@getpaseo/app -- src/components/question-form-card.utils.test.ts src/keyboard/keyboard-shortcuts.test.ts src/keyboard/keyboard-action-dispatcher.test.ts
• npm run typecheck --workspace=@getpaseo/app
• npm run typecheck

Closes #138