Rewrite Gitea download/page host to external base in update check

Gitea ROOT_URL points to an internal IP, so release/asset URLs returned
by the API are not reachable externally. Rewrite their host to the same
external base the app queries. Also prefer the .exe (NSIS) asset.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src-tauri/src/main.rs

@@ -78,10 +78,27 @@ fn export_excel(app: tauri::AppHandle, db: State<Db>, id: i64) -> Result<Option<
     excel::write_to_path(&path, &detail).map(Some)
 }
 
-/// Gitea「最新 release」API。如迁移到 https 站点，需为 ureq 启用 tls 特性。
+/// Gitea 站点根地址（应用访问用的外网主机）。如迁移到 https，需为 ureq 启用 tls 特性。
+const GITEA_BASE: &str = "http://gitea.xxhhcty.xyz:8080";
+/// Gitea「最新 release」API。
 const GITEA_LATEST_RELEASE_API: &str =
     "http://gitea.xxhhcty.xyz:8080/api/v1/repos/zcdsj/tcjs/releases/latest";
 
+/// 把 Gitea 返回的链接主机改写为 `GITEA_BASE`（保留路径/查询）。
+/// 规避 Gitea ROOT_URL 指向内网、导致外网用户打不开下载/页面链接的问题。
+fn rewrite_host(url: &str) -> String {
+    if url.is_empty() {
+        return String::new();
+    }
+    match url.find("://") {
+        Some(scheme) => match url[scheme + 3..].find('/') {
+            Some(slash) => format!("{GITEA_BASE}{}", &url[scheme + 3 + slash..]),
+            None => GITEA_BASE.to_string(),
+        },
+        None => url.to_string(),
+    }
+}
+
 #[derive(serde::Serialize)]
 struct UpdateInfo {
     current_version: String,
@@ -118,16 +135,20 @@ fn check_update(app: tauri::AppHandle) -> Result<UpdateInfo, String> {
         .trim_start_matches(['v', 'V'])
         .to_string();
     let notes = json["body"].as_str().unwrap_or_default().to_string();
-    let release_url = json["html_url"].as_str().unwrap_or_default().to_string();
+    let release_url = rewrite_host(json["html_url"].as_str().unwrap_or_default());
     let download_url = json["assets"].as_array().and_then(|assets| {
-        assets.iter().find_map(|asset| {
-            let name = asset["name"].as_str().unwrap_or_default().to_ascii_lowercase();
-            if name.ends_with(".exe") || name.ends_with(".msi") {
-                asset["browser_download_url"].as_str().map(str::to_string)
-            } else {
-                None
-            }
-        })
+        // 优先 .exe（NSIS），其次 .msi。
+        let pick = |ext: &str| {
+            assets.iter().find_map(|asset| {
+                let name = asset["name"].as_str().unwrap_or_default().to_ascii_lowercase();
+                if name.ends_with(ext) {
+                    asset["browser_download_url"].as_str()
+                } else {
+                    None
+                }
+            })
+        };
+        pick(".exe").or_else(|| pick(".msi")).map(rewrite_host)
     });
 
     Ok(UpdateInfo {
@@ -209,7 +230,20 @@ fn main() {
 
 #[cfg(test)]
 mod tests {
-    use super::is_newer;
+    use super::{is_newer, rewrite_host, GITEA_BASE};
+
+    #[test]
+    fn rewrites_internal_host_to_external() {
+        assert_eq!(
+            rewrite_host("http://10.0.11.51:3000/zcdsj/tcjs/releases/download/v0.2.0/app.exe"),
+            format!("{GITEA_BASE}/zcdsj/tcjs/releases/download/v0.2.0/app.exe")
+        );
+        assert_eq!(
+            rewrite_host("http://10.0.11.51:3000/zcdsj/tcjs/releases/tag/v0.2.0"),
+            format!("{GITEA_BASE}/zcdsj/tcjs/releases/tag/v0.2.0")
+        );
+        assert_eq!(rewrite_host(""), "");
+    }
 
     #[test]
     fn version_comparison() {