commits: tapping a changed file opens the source, not the diff #7

CommitView has two paths to two different things: a Changes row navigates to RepoRoute.file (the whole file at that commit), and a separate top-right button navigates to RepoRoute.commitDiff (the patch). Tapping a row labelled +12 -3 and getting an unannotated source file is not what it says it does.

The web has no such split. On /{owner}/{repo}/commit/{sha} the file path is a inside — clicking it expands that file's patch inline, and there is no separate diff page. The commit page is the diff.

DiffFileSection already implements exactly that, and the MR diff and CommitDiffView both use it. CommitView hand-rolls a row that links away instead. Fixing it means using DiffFileSection there, which makes the toolbar button and the commitDiff route redundant.

Dropping the route also drops the only way to open a whole file from a commit. The web does not offer that either — browse to it through the tree.