feat: edit in the Changes panel, git graph history, plan quota (v2.3.0)

- Changes panel: a working file opens in a CodeMirror editor with its diff
  inline (DiffEditor.tsx, @codemirror/merge, lazy-loaded); Changes folds the
  unchanged lines, Whole file shows them; side by side at 50/50 and full
  width; a Revert per block; original from HEAD or the branch's merge base
  (`mergeBase` on GET /git/changes?range=branch)
- Every diff: green = line added whole, red = removed whole, blue = edited
  in place (--diff-mod)
- History drawn as a commit graph (#58: `parents` on GET /git/log,
  --date-order; lib/commitGraph.ts)
- Per-workspace never-stage list, drawn orange in the Files tree (--kept);
  closed Terminal rows past three deleted
- Status bar plan quota for Claude (per account) and Codex
  (GET /api/pricing/quota, server/lib/quota.js); compact hover panel that
  stays open, Refresh button with a spinner
- Settings → Appearance holds language, theme and pet; Ctrl+Shift+C copies;
  compact sidebar navigation and short session times

client/src/lib/changeTree.ts

@@ -20,7 +20,9 @@ export interface ChangeTreeDir<T> {
 export function changeTree<T extends { path: string }>(rows: T[]): ChangeTreeDir<T> {
   const root: ChangeTreeDir<T> = { name: "", path: "", dirs: [], files: [], count: 0 };
   for (const file of rows) {
-    const parts = file.path.split("/");
+    // An untracked folder comes from git as `dir/`: a leaf named `dir/`.
+    const parts = file.path.replace(/\/$/, "").split("/");
+    if (file.path.endsWith("/")) parts[parts.length - 1] += "/";
     let dir = root;
     dir.count++;
     for (const seg of parts.slice(0, -1)) {