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/LaneGitBar.tsx

@@ -1,13 +1,14 @@
 /**
  * @file The lane's git action row: ahead/behind against the upstream, and the
  * writes `POST /api/lanes/:id/git/:action` offers that are not per-file —
- * fetch, pull, push, commit (everything, or only what the Changes panel has
- * staged), switch branch, and create/delete a branch. Per-file staging and
- * discard live in the Changes panel, beside the file they act on.
+ * fetch, pull, push, switch branch, and create/delete a branch. Committing is
+ * NOT here: it is the Changes panel's staged-only commit box, beside the
+ * per-file stage/unstage/discard it commits — one way to commit, and it only
+ * ever takes what the user staged.
  *
- * It renders beside the read-only git line in LaneCard rather than inside the
- * ⋯ menu: that menu holds the rare and dangerous (`reset worktree`), and these
- * are the opposite — the ordinary moves a lane needs several times an hour.
+ * It renders at the top of the Changes panel (`LaneGitHeader`) rather than in
+ * the lane card's ⋯ menu: that menu holds the rare and dangerous (`reset
+ * worktree`), and these are the ordinary moves a lane needs several times an hour.
  * Nothing here decides what an action may do; the server does (pull is always
  * --ff-only, switch refuses a dirty tree), and this only reports what it said.
  * Failures print git's own text, because "! [rejected] non-fast-forward" tells
@@ -17,21 +18,11 @@
 
 import { useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
-import {
-  ArrowDown,
-  ArrowUp,
-  Check,
-  GitBranch,
-  Plus,
-  RefreshCw,
-  Trash2,
-  Upload,
-  X,
-} from "lucide-react";
+import { ArrowDown, ArrowUp, GitBranch, Plus, RefreshCw, Trash2, Upload } from "lucide-react";
 import { api } from "../../lib/api";
 import type { LaneGitFacts, LaneWorktree } from "../../lib/types";
 
-type Action = "fetch" | "pull" | "push" | "commit" | "switch" | "branch-create" | "branch-delete";
+type Action = "fetch" | "pull" | "push" | "switch" | "branch-create" | "branch-delete";
 
 function Btn({
   label,
@@ -79,17 +70,15 @@ export function LaneGitBar({
   const { t } = useTranslation(["lanes"]);
   const [busy, setBusy] = useState<Action | null>(null);
   const [error, setError] = useState<string | null>(null);
-  const [committing, setCommitting] = useState(false);
-  const [message, setMessage] = useState("");
   const [switching, setSwitching] = useState(false);
   const [branches, setBranches] = useState<string[] | null>(null);
   const [worktrees, setWorktrees] = useState<LaneWorktree[]>([]);
   const [picked, setPicked] = useState("");
   const [newBranch, setNewBranch] = useState("");
-  // LaneCard is not keyed by lane, so this bar outlives a lane switch. All of
-  // the state above describes ONE lane — a message typed for lane A, Entered
-  // after switching, would commit B's whole tree under it — so it is reset
-  // during render the moment the id changes, before anything can act on it.
+  // The Changes panel is not keyed by lane, so this bar outlives a lane switch.
+  // All of the state above describes ONE lane — a branch picked for lane A,
+  // applied after switching, would move B's HEAD — so it is reset during
+  // render the moment the id changes, before anything can act on it.
   const [shownLane, setShownLane] = useState(laneId);
   // One action at a time, checked synchronously: `busy` is state, and a second
   // Enter can land before the render that disables anything.
@@ -98,8 +87,6 @@ export function LaneGitBar({
     setShownLane(laneId);
     setBusy(null);
     setError(null);
-    setCommitting(false);
-    setMessage("");
     setSwitching(false);
     setBranches(null);
     setWorktrees([]);
@@ -113,10 +100,7 @@ export function LaneGitBar({
   if (!git.available) return null;
   const dirty = git.dirty + git.untracked;
 
-  const run = async (
-    action: Action,
-    body?: { message?: string; only?: "staged"; branch?: string }
-  ) => {
+  const run = async (action: Action, body?: { branch?: string }) => {
     if (inFlight.current) return;
     inFlight.current = true;
     const lane = laneId;
@@ -127,12 +111,6 @@ export function LaneGitBar({
       // Landed after a lane switch: every write below belongs to the lane
       // no longer shown.
       if (laneNow.current !== lane) return;
-      // Only a landed commit consumes the message; a fetch or pull mid-typing
-      // must leave it where it was.
-      if (action === "commit") {
-        setCommitting(false);
-        setMessage("");
-      }
       // The branch list this bar is showing is stale the moment a branch is
       // created, deleted or switched to, so it is re-read rather than patched.
       if (action === "switch" || action.startsWith("branch-")) {
@@ -244,16 +222,6 @@ export function LaneGitBar({
           title={t("gitBar.pushHint")}
           onClick={() => run("push")}
         />
-        <Btn
-          label={t("gitBar.commit")}
-          icon={<Check className="h-3 w-3" />}
-          disabled={dirty === 0 || !!busy}
-          title={dirty === 0 ? t("gitBar.commitNothing") : t("gitBar.commitHint")}
-          onClick={() => {
-            setCommitting((v) => !v);
-            setError(null);
-          }}
-        />
         <Btn
           label={t("gitBar.switch")}
           icon={<GitBranch className="h-3 w-3" />}
@@ -265,47 +233,6 @@ export function LaneGitBar({
         />
       </div>
 
-      {committing && (
-        <div className="flex items-center gap-1.5">
-          <input
-            autoFocus
-            value={message}
-            onChange={(e) => setMessage(e.target.value)}
-            onKeyDown={(e) => {
-              if (e.key === "Enter" && message.trim() && !busy) void run("commit", { message });
-              if (e.key === "Escape") setCommitting(false);
-            }}
-            placeholder={t("gitBar.commitPlaceholder")}
-            aria-label={t("gitBar.commitPlaceholder")}
-            className="min-w-0 flex-1 rounded border border-border-light bg-surface-0 px-2 py-0.5 text-[11px] text-fg-primary placeholder:text-fg-muted focus:border-accent focus:outline-none"
-          />
-          <Btn
-            label={t("gitBar.commitAll", { count: dirty })}
-            busy={busy === "commit"}
-            disabled={!message.trim() || !!busy}
-            onClick={() => void run("commit", { message })}
-          />
-          {/* The Changes panel's per-file staging only means something if a
-              commit can take the index as it stands. The server answers
-              ENOCHANGES when nothing is staged, and that text lands below. */}
-          <Btn
-            label={t("gitBar.commitStaged")}
-            title={t("gitBar.commitStagedHint")}
-            busy={busy === "commit"}
-            disabled={!message.trim() || !!busy}
-            onClick={() => void run("commit", { message, only: "staged" })}
-          />
-          <button
-            type="button"
-            aria-label={t("gitBar.cancel")}
-            onClick={() => setCommitting(false)}
-            className="text-fg-muted hover:text-fg-primary"
-          >
-            <X className="h-3.5 w-3.5" />
-          </button>
-        </div>
-      )}
-
       {switching && (
         <div className="flex items-center gap-1.5">
           <select