[tib8]

Hovering a commit subject for one second now shows the full commit message in a wrapped tooltip. History messages load asynchronously when the tooltip opens and are cached for the displayed commit, keeping Git queries out of normal scrolling.

Issue links retain their URL tooltips. Recycled rows close the previous tooltip and ignore stale query results, and interactive rebase tooltips reflect the current edited message.

Validation:

• dotnet build src/SourceGit.csproj --no-restore passed with zero warnings and errors.
• Temporary headless UI checks passed for the hover delay, multiline message display, issue-link tooltips, edited messages, and recycled rows.

Based on the latest develop revision at submission, as required by the contributing instructions.