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

server/routes/pricing.js

@@ -6,6 +6,7 @@
 const { Router } = require("express");
 const { stmts, db } = require("../db");
 const { parseSources, sourceColumnClause } = require("../lib/source-filter");
+const { quotas } = require("../lib/quota");
 const {
   WEB_SEARCH_PER_1K_SEARCHES,
   CODE_EXEC_PER_HOUR,
@@ -508,6 +509,12 @@ router.get("/cost", (req, res) => {
   res.json({ ...result, daily_costs });
 });
 
+// GET /api/pricing/quota - plan quota spent per native tool (Claude, Codex):
+// percentages and reset times only, `?force=1` for a Refresh click (server/lib/quota.js).
+router.get("/quota", async (req, res) => {
+  res.json(await quotas({ force: req.query.force === "1" }));
+});
+
 // GET /api/pricing/cost/:sessionId - Get cost for a specific session
 router.get("/cost/:sessionId", (req, res) => {
   const rawOffset = parseInt(req.query.tz_offset, 10);