Add manual refresh button to git diff controls (#1216)

* feat(git): add manual refresh button to diff controls

Adds a checkout_refresh RPC that forces a hard re-read of the git and
GitHub snapshot plus the diff, bypassing polling. The diff controls now
show a refresh button (feature-gated) that triggers it and surfaces
errors via a toast — an escape hatch when the polled state goes stale.

* refactor(git): address review — dotted RPC name + withUnistyles

- Rename checkout_refresh RPC to the dotted convention
  (checkout.refresh.request/response) per docs/rpc-namespacing.md.
- Replace the banned useUnistyles() call in DiffRefreshButton with
  withUnistyles wrappers for the icon/spinner color, per docs/unistyles.md.

* refactor(git): move refresh into the checkout actions store

Per the feature audit: the manual refresh was the one checkout action
whose UI logic lived inline in the component instead of alongside its
siblings (commit/pull/push) in useCheckoutGitActionsStore. Move it into
the store so there's one home for "UI triggers a checkout RPC" — it now
reuses runCheckoutAction's pending/success status and query invalidation.
The component just reads status and shows an error toast.

* fix(git): size refresh loader to the icon to stop layout shift

ActivityIndicator size="small" renders ~20px regardless of platform,
wider than the 14px refresh icon, so swapping to it grew the button and
shifted the controls row. Use SyncedLoader at the same iconSize — it
renders into a size×size box, so both states share one footprint.

* fix(git): match file-explorer refresh control (RotateCw + LoadingSpinner)

Mirror the file-explorer pane's refresh button exactly: RotateCw icon,
LoadingSpinner while refreshing, both centered in a fixed icon-sized box
so the spinner can't grow the control or shift the row. Replaces the
ad-hoc RefreshCw + SyncedLoader pairing.

packages/app/src/git/actions-store.ts

@@ -28,6 +28,7 @@ export type CheckoutGitAsyncActionId =
   | "pull"
   | "push"
   | "pull-and-push"
+  | "refresh"
   | "create-pr"
   | "merge-pr-squash"
   | "merge-pr-merge"
@@ -236,6 +237,7 @@ interface CheckoutGitActionsStoreState {
   pull: (params: { serverId: string; cwd: string }) => Promise<void>;
   push: (params: { serverId: string; cwd: string }) => Promise<void>;
   pullAndPush: (params: { serverId: string; cwd: string }) => Promise<void>;
+  refresh: (params: { serverId: string; cwd: string }) => Promise<void>;
   createPr: (params: { serverId: string; cwd: string }) => Promise<void>;
   mergePr: (params: {
     serverId: string;
@@ -360,6 +362,21 @@ export const useCheckoutGitActionsStore = create<CheckoutGitActionsStoreState>()
     });
   },
 
+  refresh: async ({ serverId, cwd }) => {
+    await runCheckoutAction({
+      serverId,
+      cwd,
+      actionId: "refresh",
+      run: async () => {
+        const client = resolveClient(serverId);
+        const payload = await client.checkoutRefresh(cwd);
+        if (payload.error) {
+          throw new Error(payload.error.message);
+        }
+      },
+    });
+  },
+
   pullAndPush: async ({ serverId, cwd }) => {
     await runCheckoutAction({
       serverId,