优化 DownloadPage

[CiiLu]

• 在下载列表、模组列表中跳转时，使用 Singleton
• 在模组下载弹窗中以“依赖项”/“可选”等项目跳转时，创建新实例

[Copilot]

Pull request overview

该 PR 优化版本管理相关的模组下载跳转流程：在下载列表/模组列表跳转时复用 ui.versions.DownloadPage 单例以减少实例创建；在依赖项/可选项等弹窗内部跳转时仍创建新实例以避免状态互相干扰。

Changes:

• 将下载列表、模组列表跳转到“模组版本下载页”改为复用 Controllers 中缓存的 ui.versions.DownloadPage 实例，并通过 loadMod(...) 重载内容
• 将 ui.versions.DownloadPage 从“构造即加载”改为“可复用实例 + loadMod(...) 重新加载”
• 在依赖项条目跳转时继续创建新的 ui.versions.DownloadPage 实例并调用 loadMod(...)

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
HMCL/src/main/java/org/jackhuang/hmcl/ui/versions/ModListPageSkin.java	模组信息弹窗中跳转到下载页时改为使用单例页并调用 loadMod(...)
HMCL/src/main/java/org/jackhuang/hmcl/ui/versions/DownloadPage.java	将“按构造参数固定内容”改为“可复用页 + loadMod”，并调整加载状态重置与刷新逻辑
HMCL/src/main/java/org/jackhuang/hmcl/ui/versions/DownloadListPage.java	下载列表点击条目跳转到下载页时改为使用单例页并调用 loadMod(...)
HMCL/src/main/java/org/jackhuang/hmcl/ui/Controllers.java	新增 getDownloadVersionListPage() 返回 ui.versions.DownloadPage 的 Lazy 单例，并补充 @FXThread 注解

Comments suppressed due to low confidence (2)

HMCL/src/main/java/org/jackhuang/hmcl/ui/versions/DownloadPage.java:112

• loadModVersions() starts an async load and unconditionally applies results in whenComplete(...). When DownloadPage is reused as a singleton and loadMod(...) is called again before the previous task finishes, the earlier completion can overwrite this.versions/loaded/failed for the new addon, causing the UI to show mismatched versions. Consider adding a request/generation token (increment per loadModVersions call) and in whenComplete only apply results if the token (or current addon/repository) still matches; alternatively cancel the previous task if your task framework supports it.

        Task.supplyAsync(() -> {
            Stream<RemoteMod.Version> versions = addon.getData().loadVersions(repository, page.getDownloadProvider());
            return sortVersions(versions);
        }).whenComplete(Schedulers.javafx(), (result, exception) -> {
            if (exception == null) {
                this.versions = result;

                loaded.set(true);
                setFailed(false);
            } else {
                setFailed(true);
            }
            setLoading(false);
        }).start();

HMCL/src/main/java/org/jackhuang/hmcl/ui/versions/DownloadPage.java:90

• loadMod(...) mutates multiple JavaFX properties (loading, failed, loaded, state) and can trigger UI updates; it should be constrained to run on the FX thread to avoid undefined behavior. Consider annotating it with @FXThread (and/or asserting Platform.isFxApplicationThread()), similar to other UI entrypoints in Controllers.

    public void loadMod(DownloadListPage page, RemoteMod addon, Profile.ProfileVersion version, @Nullable DownloadCallback callback) {
        this.page = page;
        this.repository = page.repository;
        this.addon = addon;
        this.translations = ModTranslations.getTranslationsByRepositoryType(repository.getType());
        this.mod = translations.getModByCurseForgeId(addon.getSlug());
        this.version = version;
        this.callback = callback;
        loadModVersions();

        this.state.set(State.fromTitle(addon.getTitle()));
    }

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[Copilot]

The identifier downloadVersionListPage is a bit misleading because it holds a ui.versions.DownloadPage (mod version details), not a list page. Consider renaming it (and the accessor) to something like downloadVersionPage/downloadModVersionPage to avoid confusion with DownloadListPage and ui.download.DownloadPage.

[Copilot]

Method name getDownloadVersionListPage() suggests returning a list page, but it returns a ui.versions.DownloadPage instance. Renaming the method to match the actual UI concept (e.g., getDownloadVersionPage) would make call sites clearer.

Suggested change

	public static org.jackhuang.hmcl.ui.versions.DownloadPage getDownloadVersionListPage() {
	public static org.jackhuang.hmcl.ui.versions.DownloadPage getDownloadVersionPage() {

[Glavo]

真的有必要减少创建新实例？我觉得似乎意义不大。