feat: support cancellable official sync

infrastructure/src/official_download.rs

@@ -332,6 +332,17 @@ impl OfficialResourcePullService {
         &self,
         plan: &OfficialResourcePullPlan,
         mut progress: impl FnMut(OfficialResourcePullProgress),
+    ) -> Result<OfficialResourcePullReport, String> {
+        self.pull_with_progress_and_cancellation(plan, &mut progress, || false)
+    }
+
+    /// Executes the plan, emits URL progress, and aborts between URLs when
+    /// `should_cancel` returns true.
+    pub fn pull_with_progress_and_cancellation(
+        &self,
+        plan: &OfficialResourcePullPlan,
+        mut progress: impl FnMut(OfficialResourcePullProgress),
+        mut should_cancel: impl FnMut() -> bool,
     ) -> Result<OfficialResourcePullReport, String> {
         fs::create_dir_all(&self.output_root).map_err(|error| {
             format!(
@@ -347,6 +358,10 @@ impl OfficialResourcePullService {
         let total = urls.len();
         let mut items = Vec::new();
         for (offset, url) in urls.into_iter().enumerate() {
+            if should_cancel() {
+                return Err("official resource pull interrupted by shutdown request".to_string());
+            }
+
             let index = offset + 1;
             progress(OfficialResourcePullProgress::started(
                 index,
@@ -400,6 +415,10 @@ impl OfficialResourcePullService {
             });
         }
 
+        if should_cancel() {
+            return Err("official resource pull interrupted by shutdown request".to_string());
+        }
+
         let verified_hashes = self.verify_downloaded_official_hashes(&official_hash_pairs)?;
 
         Ok(OfficialResourcePullReport {