An empty diff says "No changes." in one plain muted line, not a boxed card #10063

An empty diff now renders through the shared empty() block, which has no card class, and says "No changes." There's a test for it. bun test on test/diff.test.ts, test/empty-language.test.ts and test/diff-review-comment.test.ts, bun scripts/design-lint.ts and tsc --noEmit pass.

renderDiff in src/web/diff-view.ts was already a bare <div class="empty"> before this change; an earlier change (#10018) had already moved empty() off the card. So the visible change is small: it now goes through empty() (from src/web/ui.ts) rather than a hand-written div. That is the plain block the issue asks for.

The new test, in test/diff.test.ts, asserts the output contains "No changes.", has class="empty", and has no card class anywhere.

I didn't run the full suite; the forge runs it on push. The diff also shows more lines changed in src/web/diff-view.ts than I edited, because I ran prettier on it and test/diff.test.ts.

Closes #10046

An empty diff now says "No changes." as one plain muted block with no card class, and a test covers it.

The first push failed the forge's gate because no commit message had a Try: line. I added an empty commit that has one: open a pull with no changed files on the preview and look at its Files tab. bun scripts/gate.ts now passes locally. I didn't re-run tsc or the tests for this push, since the commit is empty and changes no files.

• Code: renderDiff in src/web/diff-view.ts now renders the empty case through the shared empty() block. Before this, it was already a bare <div class="empty"> without a card, from an earlier change (#10018).
• Test: the new test is in test/diff.test.ts. It asserts the text "No changes." is present, the block has class="empty", and no card class appears anywhere.

I ran prettier on both changed files, so the diff shows more changed lines in src/web/diff-view.ts than I edited.

I've made both changes you asked for and pushed them to the same branch.

• Revert: I took src/web/diff-view.ts back to its main version and reapplied only the change. The diff is now two lines: the empty import and return empty({ title: "No changes." }) in renderDiff. The resolved by and file-count reflows are gone.
• Test: the test in test/diff.test.ts now asserts <p class="empty-title">No changes.</p>, which only the shared empty() block produces. It still asserts there is no card class. I didn't run the test against the old code, but the old bare div had no <p class="empty-title">, so it would have failed there.

The tests in test/diff.test.ts, tsc, bun scripts/design-lint.ts and bun scripts/gate.ts all pass. I put the Try: line in this commit as well.