fix(run,lanes): prompt autocomplete, per-lane Active runs, compact Changes header

- The run form's prompt box offers suggestions again: `/` lists the run
  cwd's project and user commands and skills plus the CLI built-ins
  (claude lanes only), `@` lists files under the cwd; Enter picks while
  the list is open and sends otherwise. The 2f39f4e rewrite had left a
  bare textarea that ignored both.
- Active runs lists only the current lane's runs and external sessions
  (sessions matched to the lane by longest path-boundary cwd), instead of
  every lane's.
- The Changes panel's git line and its actions are one compact row in one
  card, and the mode/range toolbar is one wrapping row.
- The lane card hides itself when it has nothing to show, instead of
  leaving an empty frame where the git row used to be.

client/src/components/lanes/LaneGitBar.tsx

@@ -6,8 +6,8 @@
  * per-file stage/unstage/discard it commits — one way to commit, and it only
  * ever takes what the user staged.
  *
- * 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
+ * It renders at the top of the Changes panel (`LaneGitHeader`), its actions as
+ * icons on the same row as the branch line, 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.
@@ -30,6 +30,7 @@ function Btn({
   busy,
   disabled,
   title,
+  compact,
   onClick,
 }: {
   label: string;
@@ -37,6 +38,8 @@ function Btn({
   busy?: boolean;
   disabled?: boolean;
   title?: string;
+  /** Icon only; the label becomes the accessible name, the hint the tooltip. */
+  compact?: boolean;
   onClick: () => void;
 }) {
   return (
@@ -45,10 +48,13 @@ function Btn({
       onClick={onClick}
       disabled={disabled || busy}
       title={title}
-      className="flex items-center gap-1 rounded border border-border-light px-1.5 py-0.5 text-[11px] text-fg-secondary transition-colors hover:bg-surface-2 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40"
+      aria-label={compact ? label : undefined}
+      className={`flex items-center gap-1 rounded text-[11px] text-fg-secondary transition-colors hover:bg-surface-3 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40 ${
+        compact ? "h-6 w-6 justify-center" : "border border-border-light px-1.5 py-0.5"
+      }`}
     >
       {icon}
-      {label}
+      {!compact && label}
     </button>
   );
 }
@@ -58,9 +64,13 @@ export function LaneGitBar({
   git,
   onChanged,
   onNewLane,
+  lead,
 }: {
   laneId: number;
   git: LaneGitFacts;
+  /** Rendered at the start of the action row: the header's branch line, so
+   *  the facts and the buttons that act on them read as one row. */
+  lead?: React.ReactNode;
   /** Called after any action that could have moved the working copy. */
   onChanged: () => void;
   /** Open the Add-lane flow for a sibling worktree of this repo, optionally on
@@ -165,8 +175,9 @@ export function LaneGitBar({
   );
 
   return (
-    <div data-testid="lane-git-bar" className="mb-2 space-y-1">
-      <div className="flex flex-wrap items-center gap-1.5">
+    <div data-testid="lane-git-bar" className="space-y-1">
+      <div className="flex min-w-0 items-center gap-2">
+        {lead}
         {/* Ahead/behind first: it is the fact that decides which of the
             buttons beside it the user actually wants. */}
         {/* Null counts with an upstream named means git could not compare
@@ -176,7 +187,7 @@ export function LaneGitBar({
           <span
             data-testid="lane-git-tracking"
             title={git.upstream}
-            className="flex items-center gap-1 font-mono text-[11px] text-fg-muted"
+            className="flex shrink-0 items-center gap-1 font-mono text-[11px] text-fg-muted"
           >
             {(git.ahead ?? 0) > 0 && (
               <span className="flex items-center text-status-warning">
@@ -194,43 +205,51 @@ export function LaneGitBar({
           </span>
         ) : (
           git.hasRemote && (
-            <span className="font-mono text-[11px] text-fg-muted">{t("gitBar.noUpstream")}</span>
+            <span className="shrink-0 font-mono text-[11px] text-fg-muted">
+              {t("gitBar.noUpstream")}
+            </span>
           )
         )}
 
-        <Btn
-          label={t("gitBar.fetch")}
-          icon={<RefreshCw className="h-3 w-3" />}
-          busy={busy === "fetch"}
-          disabled={!git.hasRemote || !!busy}
-          title={t("gitBar.fetchHint")}
-          onClick={() => run("fetch")}
-        />
-        <Btn
-          label={t("gitBar.pull")}
-          icon={<ArrowDown className="h-3 w-3" />}
-          busy={busy === "pull"}
-          disabled={!git.hasRemote || !!busy}
-          title={t("gitBar.pullHint")}
-          onClick={() => run("pull")}
-        />
-        <Btn
-          label={t("gitBar.push")}
-          icon={<Upload className="h-3 w-3" />}
-          busy={busy === "push"}
-          disabled={!git.hasRemote || !!busy}
-          title={t("gitBar.pushHint")}
-          onClick={() => run("push")}
-        />
-        <Btn
-          label={t("gitBar.switch")}
-          icon={<GitBranch className="h-3 w-3" />}
-          disabled={!!busy}
-          // A dirty tree is refused server-side; saying so before the click
-          // beats a red box after it.
-          title={dirty > 0 ? t("gitBar.switchDirty") : t("gitBar.switchHint")}
-          onClick={openSwitch}
-        />
+        <div className="ml-auto flex shrink-0 items-center">
+          <Btn
+            compact
+            label={t("gitBar.fetch")}
+            icon={<RefreshCw className="h-3.5 w-3.5" />}
+            busy={busy === "fetch"}
+            disabled={!git.hasRemote || !!busy}
+            title={t("gitBar.fetchHint")}
+            onClick={() => run("fetch")}
+          />
+          <Btn
+            compact
+            label={t("gitBar.pull")}
+            icon={<ArrowDown className="h-3.5 w-3.5" />}
+            busy={busy === "pull"}
+            disabled={!git.hasRemote || !!busy}
+            title={t("gitBar.pullHint")}
+            onClick={() => run("pull")}
+          />
+          <Btn
+            compact
+            label={t("gitBar.push")}
+            icon={<Upload className="h-3.5 w-3.5" />}
+            busy={busy === "push"}
+            disabled={!git.hasRemote || !!busy}
+            title={t("gitBar.pushHint")}
+            onClick={() => run("push")}
+          />
+          <Btn
+            compact
+            label={t("gitBar.switch")}
+            icon={<GitBranch className="h-3.5 w-3.5" />}
+            disabled={!!busy}
+            // A dirty tree is refused server-side; saying so before the click
+            // beats a red box after it.
+            title={dirty > 0 ? t("gitBar.switchDirty") : t("gitBar.switchHint")}
+            onClick={openSwitch}
+          />
+        </div>
       </div>
 
       {switching && (