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/server/src/server/session.ts

@@ -2033,6 +2033,8 @@ export class Session {
         return this.handleCheckoutPullRequest(msg);
       case "checkout_push_request":
         return this.handleCheckoutPushRequest(msg);
+      case "checkout.refresh.request":
+        return this.handleCheckoutRefreshRequest(msg);
       case "checkout_pr_create_request":
         return this.handleCheckoutPrCreateRequest(msg);
       case "checkout_pr_merge_request":
@@ -5297,6 +5299,41 @@ export class Session {
     }
   }
 
+  private async handleCheckoutRefreshRequest(
+    msg: Extract<SessionInboundMessage, { type: "checkout.refresh.request" }>,
+  ): Promise<void> {
+    const { cwd, requestId } = msg;
+
+    try {
+      this.github.invalidate({ cwd });
+      await this.workspaceGitService.getSnapshot(cwd, {
+        force: true,
+        includeGitHub: true,
+        reason: "manual-refresh",
+      });
+      this.checkoutDiffManager.scheduleRefreshForCwd(cwd);
+      this.emit({
+        type: "checkout.refresh.response",
+        payload: {
+          cwd,
+          success: true,
+          error: null,
+          requestId,
+        },
+      });
+    } catch (error) {
+      this.emit({
+        type: "checkout.refresh.response",
+        payload: {
+          cwd,
+          success: false,
+          error: toCheckoutError(error),
+          requestId,
+        },
+      });
+    }
+  }
+
   private async handleCheckoutPrCreateRequest(
     msg: Extract<SessionInboundMessage, { type: "checkout_pr_create_request" }>,
   ): Promise<void> {