Address board UX review feedback

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/CommentThread.tsx

@@ -423,6 +423,7 @@ export function CommentThread({
 
     setSubmitting(true);
     try {
+      // TODO: wire an explicit "send + interrupt" action through the composer if we expose it in the UI.
       await onAdd(trimmed, reopen ? true : undefined, reassignment ?? undefined);
       setBody("");
       if (draftKey) clearDraft(draftKey);

ui/src/components/SwipeToArchive.test.tsx

@@ -136,7 +136,7 @@ describe("SwipeToArchive", () => {
 
     const surface = container.querySelector("[data-inbox-row-surface]") as HTMLDivElement | null;
     expect(surface).not.toBeNull();
-    expect(surface?.style.backgroundColor).toBe("rgb(243, 244, 246)");
+    expect(surface?.style.backgroundColor).toBe("hsl(var(--muted))");
     expect(surface?.style.boxShadow).toBe("");
 
     act(() => {

ui/src/components/SwipeToArchive.tsx

@@ -13,7 +13,7 @@ interface SwipeToArchiveProps {
 const COMMIT_THRESHOLD = 0.32;
 const MAX_SWIPE = 0.88;
 const COMMIT_DELAY_MS = 140;
-const SELECTED_ROW_BACKGROUND = "#f3f4f6";
+const SELECTED_ROW_BACKGROUND = "hsl(var(--muted))";
 
 export function SwipeToArchive({
   children,