feat(lanes): move the lane's git section into the Changes panel

- The branch line, the uncommitted-files hover panel and the git action
  row (fetch/pull/push/branch) move from the lane card to the top of the
  Changes panel (new LaneGitHeader.tsx); the card has no git row now.
- Header and panel share one git-facts read: stage/unstage/discard/commit
  and Refresh re-read it, and a git bar action re-reads the diff, the
  history and the file tree.
- The git bar no longer commits: the panel's staged-only box is the one
  commit path. Orphaned gitBar.commit*/cancel strings removed (en, vi).
- "New lane here" is wired from Workspace to the panel.

client/src/components/lanes/LaneChangesPanel.tsx

@@ -45,6 +45,7 @@ import {
 } from "lucide-react";
 import { api } from "../../lib/api";
 import { LaneDiffView, LaneFileView, type DiffLayout } from "./LaneDiffView";
+import { LaneGitHeader, useLaneGitFacts } from "./LaneGitHeader";
 import type {
   LaneChangeFile,
   LaneChangeRange,
@@ -64,7 +65,7 @@ const TREE_CONCURRENCY = 4;
 
 type Mode = "overview" | "review" | "file" | "history" | "browse";
 
-/** Colour per porcelain status letter, matching LaneCard's file panel. */
+/** Colour per porcelain status letter, matching LaneGitHeader's file panel. */
 function statusClass(status: string, untracked: boolean) {
   if (untracked) return "text-status-success";
   const code = status.trim()[0];
@@ -281,8 +282,21 @@ function ChangeRow({
   );
 }
 
-export function LaneChangesPanel({ laneId }: { laneId: number }) {
+export function LaneChangesPanel({
+  laneId,
+  onNewLane,
+}: {
+  laneId: number;
+  /** Open the Add-lane flow for a sibling worktree; see `LaneGitBar`. */
+  onNewLane?: (branch?: string) => void;
+}) {
   const { t } = useTranslation(["lanes"]);
+  // One read of the working copy, shared by the header and every write below:
+  // a stage, a discard or a commit changes the counts the header shows.
+  const [git, refreshGit] = useLaneGitFacts(laneId);
+  // Bumped by Refresh and by a git bar action: a pull or a switch moves
+  // history and the tree too, not just the diff `load` re-reads.
+  const [reread, setReread] = useState(0);
   const [range, setRange] = useState<LaneChangeRange>("work");
   const [mode, setMode] = useState<Mode>("overview");
   const [openFile, setOpenFile] = useState<string | null>(null);
@@ -384,7 +398,7 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
       .gitLog(laneId, { limit: 50 })
       .then(forLane(laneId, (r) => setCommits(r.commits)))
       .catch((err) => setError(err instanceof Error ? err.message : String(err)));
-  }, [mode, laneId]);
+  }, [mode, laneId, reread]);
 
   useEffect(() => {
     if (mode !== "browse" || query.trim() || "" in treeChildren) return;
@@ -394,7 +408,7 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
       .catch((err) => setError(err instanceof Error ? err.message : String(err)));
     // `treeChildren` is the cache this fills — reading it as a dep would loop.
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [mode, laneId, query]);
+  }, [mode, laneId, query, reread]);
 
   // A folder's children are fetched lazily, the first time it is expanded.
   const toggleDir = (path: string) => {
@@ -555,6 +569,7 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
       await api.lanes.gitAction(lane, action, { paths: [path], ...(confirm ? { confirm } : {}) });
       if (laneNow.current !== lane) return;
       setConfirmDiscard(null);
+      refreshGit();
       await load();
     } catch (err) {
       if (laneNow.current === lane) setError(err instanceof Error ? err.message : String(err));
@@ -574,6 +589,7 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
       await api.lanes.gitAction(lane, "commit", { message: message.trim(), only: "staged" });
       if (laneNow.current !== lane) return;
       setMessage("");
+      refreshGit();
       await load();
     } catch (err) {
       if (laneNow.current === lane) setError(err instanceof Error ? err.message : String(err));
@@ -582,6 +598,15 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
     }
   };
 
+  const rereadAll = () => {
+    refreshGit();
+    // The tree cache is dropped whole: after a switch any folder may differ.
+    setTreeChildren({});
+    setExpandedDirs(new Set());
+    setReread((n) => n + 1);
+    void load();
+  };
+
   const toggleCollapsed = (path: string) =>
     setCollapsed((prev) => {
       const next = new Set(prev);
@@ -604,6 +629,7 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
 
   return (
     <div data-testid="lane-changes" className="flex min-h-0 flex-1 flex-col">
+      <LaneGitHeader laneId={laneId} git={git} onChanged={rereadAll} onNewLane={onNewLane} />
       {/* Two rows on purpose: WHERE you are (mode, and the refresh that always
           applies) on top, HOW you are looking at it (range, layout, context,
           whole file) underneath. One row wrapped mid-group as soon as the
@@ -648,7 +674,7 @@ export function LaneChangesPanel({ laneId }: { laneId: number }) {
 
           <button
             type="button"
-            onClick={() => void load()}
+            onClick={rereadAll}
             aria-label={t("changes.refresh")}
             title={t("changes.refresh")}
             className="ml-auto shrink-0 text-fg-muted hover:text-fg-primary"