Improve Git History navigation and asynchronous UI safety

Add a History ref selector for HEAD, local branches, remote branches, and tags without requiring checkout. Reuse cached branch-model display strings to keep large ref lists efficient.
Make deferred main-thread callbacks lifetime-safe across ecode controllers and plugins. Initialize plugin dispatchers during UIReady and extend MainThreadLifetime to support delayed and tagged dispatch.
Fix expandable Git History rows, empty merge projections, and commit-description expansion. Display only the physical first line while collapsed and avoid duplicating it in the expanded body.
Add coverage for history ref handling and preserve stale-request guards during repository and revision changes.
Fix UIImageViewer dimension reporting for sprites by displaying the underlying texture dimensions.
The Git History interface remains a work in progress.

bin/assets/i18n/zh.xml

@@ -1052,6 +1052,10 @@ file in the directory tree.</string>
 	<string name="git_history_refresh">刷新</string>
 	<string name="git_history_load_older">加载更早的提交</string>
 	<string name="git_history_empty">尚无提交</string>
+	<string name="git_history_no_additional_commits">没有其他提交</string>
 	<string name="git_history_error">无法加载 Git 历史记录</string>
 	<string name="git_history_retry">重试</string>
+	<string name="git_local_branch">本地</string>
+	<string name="git_remote_branch">远程</string>
+	<string name="git_tag">标签</string>
 </resources>