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/__tests__/changeTree.test.ts

@@ -40,3 +40,12 @@ describe("changeTree", () => {
     expect(treeFiles(root.dirs[0]!).map((f) => f.path)).toHaveLength(3);
   });
 });
+
+describe("changeTree — an untracked folder", () => {
+  it("shows git's `dir/` entry as a named row in its parent folder", () => {
+    const root = changeTree([{ path: "docs/plans/analytics-parity/" }, { path: "docs/x.md" }]);
+    const docs = root.dirs[0]!;
+    expect(docs.files.map((f) => f.name)).toEqual(["x.md"]);
+    expect(docs.dirs[0]!.files.map((f) => f.name)).toEqual(["analytics-parity/"]);
+  });
+});