fix(reviewManager): use pr.base.ref instead of pr.base.name in hasBranch call (#8698)

pr.base.ref is the branch name (e.g., "main") while
pr.base.name is the repository name. hasBranch() expects a branch
name, so passing pr.base.name would always query refs/heads/<repo-name>
which never matches an actual branch.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: Will-hxw

src/view/reviewManager.ts

@@ -543,7 +543,7 @@ export class ReviewManager extends Disposable {
 			Logger.appendLine('Resolving pull request', this.id);
 			let pr = await this._folderRepoManager.resolvePullRequest(owner, repositoryName, metadata.prNumber, useCache);
 
-			if (!pr || !pr.isResolved() || !(await pr.githubRepository.hasBranch(pr.base.name))) {
+			if (!pr || !pr.isResolved() || !(await pr.githubRepository.hasBranch(pr.base.ref))) {
 				await this.clear(true);
 				this._prNumber = undefined;
 				Logger.appendLine('This PR is no longer valid', this.id);