Create command palette and add new features for search and actions (#728)

* refactor(ui): replace in-repo Command primitive with cmdk wrapper

* feat(command-palette): add global Cmd+K palette with v1 actions

* feat(command-palette): add session, file, and commit search sources

* refactor: add provider names to model constants

* feat(command-palette): add settings, navigation, message search, and ⌘K hints

* feat(command-palette): add git fetch/pull/push and branch switch actions

* refactor(command-palette): consolidate fetch source hooks behind useApiSource

* refactor(command-palette): extract useCommandKey and SETTINGS_MAIN_TABS metadata

* refactor(command-palette): extract groups into declarative registry

* refactor(command-palette): wire openFile through PaletteOpsContext

* refactor: migrate openSettings and refreshProjects from window.* to PaletteOpsContext

* refactor(command-palette): inline groups and delete registry indirection

* refactor(command-palette): return items array directly from source hooks

* refactor(palette-ops): flatten Handle wrapper into ref-based registry

* refactor: inline useCommandKey as MOD_KEY constant in two call sites

* feat: introduce pages and fix bug on branch switching

* fix: small labels

* fix: coderabbit issues

* fix: coderabbit comments

* Update src/components/chat/view/subcomponents/ProviderSelectionEmptyState.tsx

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

src/contexts/PaletteOpsContext.tsx

@@ -0,0 +1,53 @@
+import { createContext, useContext, useEffect, useMemo, useRef } from 'react';
+import type { MutableRefObject, ReactNode } from 'react';
+
+export type PaletteOps = {
+  openFile: (path: string) => void;
+  openSettings: (tab?: string) => void;
+  refreshProjects: () => Promise<void> | void;
+};
+
+type Registry = MutableRefObject<Partial<PaletteOps>>;
+
+const PaletteOpsContext = createContext<Registry | null>(null);
+
+const defaultOps: PaletteOps = {
+  openFile: () => undefined,
+  openSettings: () => undefined,
+  refreshProjects: () => undefined,
+};
+
+export function PaletteOpsProvider({ children }: { children: ReactNode }) {
+  const ref = useRef<Partial<PaletteOps>>({});
+  return <PaletteOpsContext.Provider value={ref}>{children}</PaletteOpsContext.Provider>;
+}
+
+export function usePaletteOps(): PaletteOps {
+  const ref = useContext(PaletteOpsContext);
+  return useMemo<PaletteOps>(
+    () => ({
+      openFile: (path) => (ref?.current.openFile ?? defaultOps.openFile)(path),
+      openSettings: (tab) => (ref?.current.openSettings ?? defaultOps.openSettings)(tab),
+      refreshProjects: () => (ref?.current.refreshProjects ?? defaultOps.refreshProjects)(),
+    }),
+    [ref],
+  );
+}
+
+export function usePaletteOpsRegister(partial: Partial<PaletteOps>) {
+  const ref = useContext(PaletteOpsContext);
+  const { openFile, openSettings, refreshProjects } = partial;
+
+  useEffect(() => {
+    if (!ref) return undefined;
+    const prev = { ...ref.current };
+    if (openFile) ref.current.openFile = openFile;
+    if (openSettings) ref.current.openSettings = openSettings;
+    if (refreshProjects) ref.current.refreshProjects = refreshProjects;
+    return () => {
+      if (openFile && ref.current.openFile === openFile) ref.current.openFile = prev.openFile;
+      if (openSettings && ref.current.openSettings === openSettings) ref.current.openSettings = prev.openSettings;
+      if (refreshProjects && ref.current.refreshProjects === refreshProjects) ref.current.refreshProjects = prev.refreshProjects;
+    };
+  }, [ref, openFile, openSettings, refreshProjects]);
+}