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/pages/Workspace.tsx

@@ -1275,6 +1275,7 @@ export function Workspace() {
                       laneId={panelAt.laneId}
                       session={panelAt.session}
                       full={changesFull}
+                      wide={changesPreset !== "compact"}
                       onDirtyChange={setChangesDirty}
                       // A sibling worktree forks from the lane's SOURCE repo when
                       // it has one (this lane is itself a worktree of it); an
@@ -1310,7 +1311,13 @@ export function Workspace() {
                     {tLanes("changes.title")}
                   </span>
                 </button>
-                {panelAt && <LaneGitRailCounts laneId={panelAt.laneId} session={panelAt.session} />}
+                {panelAt && (
+                  <LaneGitRailCounts
+                    laneId={panelAt.laneId}
+                    session={panelAt.session}
+                    onShowAll={() => setChangesOpen(true)}
+                  />
+                )}
               </div>
             ))}
         </div>