feat(ui): add session history navigation, permission keys, and review shortcuts

mod+alt+arrows step through this window's session-open history (or between
neighbouring tabs when session tabs are on), mod+k r renames the current
session inline, and mod+k a toggles permission auto-accept. Pending
permission cards respond to alt+enter / alt+shift+enter / alt+backspace with
the keys printed on the buttons. The commit message box commits on
mod+enter, alt+arrows step the diff review between changed files, and the
command palette gains search-only commands for rare actions so the initial
list stays short.

packages/ui/src/lib/sessionNavigationHistory.ts

@@ -0,0 +1,61 @@
+import { useSessionUIStore } from '@/sync/session-ui-store';
+import { useGlobalSessionsStore, resolveGlobalSessionDirectory } from '@/stores/useGlobalSessionsStore';
+
+// Browser-style back/forward over the order sessions were opened in this
+// window. A normal session switch truncates the forward part and appends;
+// stepping through history moves only the cursor, so back stays back even
+// after several presses. In-memory by design: the stack describes this
+// window's journey, not durable state.
+
+const MAX_HISTORY = 100;
+
+let visitedSessionIds: string[] = [];
+let cursor = -1;
+let navigating = false;
+
+const recordVisit = (sessionId: string): void => {
+  if (visitedSessionIds[cursor] === sessionId) return;
+  visitedSessionIds = [...visitedSessionIds.slice(0, cursor + 1), sessionId].slice(-MAX_HISTORY);
+  cursor = visitedSessionIds.length - 1;
+};
+
+useSessionUIStore.subscribe((state, previousState) => {
+  if (state.currentSessionId === previousState.currentSessionId) return;
+  if (!state.currentSessionId || navigating) return;
+  recordVisit(state.currentSessionId);
+});
+
+/**
+ * Steps the current session back (-1) or forward (+1) through this window's
+ * open history. Entries whose session no longer exists in the loaded list are
+ * skipped and dropped. Returns false when there is nowhere to go.
+ */
+export const navigateSessionHistory = (delta: -1 | 1): boolean => {
+  const sessionsById = new Map(
+    useGlobalSessionsStore.getState().activeSessions.map((session) => [session.id, session] as const),
+  );
+  let nextCursor = cursor + delta;
+  while (nextCursor >= 0 && nextCursor < visitedSessionIds.length) {
+    const session = sessionsById.get(visitedSessionIds[nextCursor]);
+    if (session) {
+      cursor = nextCursor;
+      navigating = true;
+      try {
+        useSessionUIStore.getState().setCurrentSession(session.id, resolveGlobalSessionDirectory(session));
+      } finally {
+        navigating = false;
+      }
+      return true;
+    }
+    // Drop the dead entry at nextCursor and keep scanning in the same
+    // direction: a removal shifts later entries one index down, so the next
+    // forward candidate lands on the same index while a backward scan steps.
+    visitedSessionIds = [
+      ...visitedSessionIds.slice(0, nextCursor),
+      ...visitedSessionIds.slice(nextCursor + 1),
+    ];
+    if (nextCursor < cursor) cursor -= 1;
+    if (delta < 0) nextCursor -= 1;
+  }
+  return false;
+};