fix: skip version check for preview channel and add upload progress bar

Co-authored-by: Rain-kl <63696351+Rain-kl@users.noreply.github.com>

atsf_server/service/update.go

@@ -376,7 +376,15 @@ func buildLatestServerReleaseView(release *githubReleaseResponse, channel Releas
 	isDevBuild := currentVersion == "" || strings.EqualFold(currentVersion, "dev")
 	hasUpdate := false
 	if release != nil && !isDevBuild {
-		hasUpdate = isVersionNewer(currentVersion, release.TagName)
+		if channel == ReleaseChannelPreview {
+			// Preview releases use a "major.minor.patch-git-<commit>" scheme that cannot
+			// be meaningfully compared against the running stable version, so we skip the
+			// version check and always allow upgrading when the user explicitly selects
+			// the preview channel.
+			hasUpdate = true
+		} else {
+			hasUpdate = isVersionNewer(currentVersion, release.TagName)
+		}
 	}
 
 	serverUpgradeState.Lock()

atsf_server/service/update_test.go

@@ -140,6 +140,36 @@ func TestBuildLatestServerReleaseViewPreview(t *testing.T) {
 	}
 }
 
+// TestBuildLatestServerReleaseViewPreviewBypassVersionCheck verifies that switching to
+// the preview channel always reports has_update=true, even when the preview tag uses a
+// "major.minor.patch-git-<commit>" scheme that would otherwise compare as equal-or-older
+// than the currently running stable version.
+func TestBuildLatestServerReleaseViewPreviewBypassVersionCheck(t *testing.T) {
+	originalVersion := common.Version
+	common.Version = "v1.0.0"
+	t.Cleanup(func() {
+		common.Version = originalVersion
+		resetServerUpgradeTestState(t)
+	})
+
+	// A typical preview tag: same base version as stable but with a git-commit suffix.
+	// Without the bypass, isVersionNewer("v1.0.0", "v1.0.0-git-abc1234") returns false
+	// because a version without a prerelease identifier is considered higher than one
+	// with a prerelease identifier under semver rules.
+	view := buildLatestServerReleaseView(&githubReleaseResponse{
+		TagName:     "v1.0.0-git-abc1234",
+		Prerelease:  true,
+		PublishedAt: "2026-03-12T00:00:00Z",
+	}, ReleaseChannelPreview)
+
+	if !view.HasUpdate {
+		t.Fatal("expected preview channel to bypass version comparison and report has_update=true")
+	}
+	if view.Channel != ReleaseChannelPreview.String() {
+		t.Fatalf("unexpected channel: %s", view.Channel)
+	}
+}
+
 func TestUploadManualServerBinary(t *testing.T) {
 	originalVersion := common.Version
 	common.Version = "v0.4.0"