refactor(sidebar): extract InlineRename, InlineConfirm, and NavItem

FolderItem and AlbumItem each carried their own copy of the in-place
rename input (state, select-on-open effect, commit/cancel handling) and
the Confirm/Cancel pair for destructive actions. Both are now shared
components: InlineRename mounts fresh per rename (an external name
change mid-rename no longer clobbers typing), InlineConfirm is the
compact red/gray pair. The four copy-pasted nav rows collapse into a
local NavItem component.

src/components/InlineConfirm.tsx

@@ -0,0 +1,28 @@
+/**
+ * Compact Confirm/Cancel pair for destructive row actions (remove folder,
+ * delete album). Swap it in where the hover actions normally sit.
+ */
+export function InlineConfirm({
+  onConfirm,
+  onCancel,
+}: {
+  onConfirm: () => void;
+  onCancel: () => void;
+}) {
+  return (
+    <div className="flex items-center gap-1 shrink-0" onClick={(event) => event.stopPropagation()}>
+      <button
+        className="px-1.5 py-0.5 text-[10px] rounded bg-red-500/20 text-red-400 hover:bg-red-500/30 hover:text-red-300 transition-colors"
+        onClick={onConfirm}
+      >
+        Confirm
+      </button>
+      <button
+        className="px-1.5 py-0.5 text-[10px] rounded bg-white/5 text-gray-500 hover:bg-white/10 hover:text-gray-300 transition-colors"
+        onClick={onCancel}
+      >
+        Cancel
+      </button>
+    </div>
+  );
+}