fix: render tabs in commit messages as spaces

[costajohnt]

This Pull Request fixes/closes #3036.

On v0.28.1 a tab in a commit message reaches the terminal, moves the cursor to the next tab stop, and ratatui loses track of what's on screen, so the commit list row comes out scrambled and old text is left behind. On current master ratatui 0.30 strips the control character instead, so PR:\t123 shows as PR:123. This converts tabs to spaces with the existing string_utils::tabs_to_spaces, the same way the diff and blame views already do.

It changes the following:

• commit details view: subject and body (wrap_commit_details), with a unit test
• commit list entries (LogEntry::from), which covers the revlog, stash list and file history
• compare view subject and the "Files at ..." title in the revision files view
• the commit/amend popup is left alone, since that text is edited and written back as the commit message

Checked with a scratch repo committed with $'subj\twith tab\n\nPR:\t299119', opened in a 120x30 terminal:

Build	Commit list row	Details pane
v0.28.1	subjubj witab	subj with tab / PR: 299119
master	subjwith tab	subjwith tab / PR:299119
this branch	subj with tab	subj with tab / PR: 299119

I followed the checklist:

• I added unittests
• I ran make check without errors (ran its steps individually: cargo fmt -- --check, cargo clippy --workspace --all-features, cargo test --workspace (320 passed) and cargo deny check are clean; I don't have cargo-nextest or cargo-sort installed, and no Cargo.toml changed)
• I tested the overall application
• I added an appropriate item to the changelog