feat: add `reprove` command for re-proving theorems with a specified tactic (#10434)

This PR adds `reprove N by T`, which effectively elaborates `example
type_of% N := by T`. It supports multiple identifiers. This is useful
for testing tactics.


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

---------

Co-authored-by: Claude <noreply@anthropic.com>
3 files changed