Mirror remotes are independent, so their iteration order carries no
meaning; a HashMap drops the BTreeMap's unneeded ordering guarantee.

Assisted-by: Claude Opus 4.8 via Claude Code

diff --git a/quire-server/src/quire/mod.rs b/quire-server/src/quire/mod.rs
index 47ef926..09f851a 100644
--- a/quire-server/src/quire/mod.rs
+++ b/quire-server/src/quire/mod.rs
@@ -1,4 +1,4 @@
-use std::collections::{BTreeMap, HashMap};
+use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 use std::sync::{Arc, Mutex, OnceLock};
 
@@ -192,7 +192,7 @@ pub struct RepoConfig {
     /// Remotes to mirror every pushed ref to, keyed by remote URL. Each
     /// value names the global `:secrets` entry holding that remote's push
     /// token. Empty disables mirroring.
-    pub mirrors: BTreeMap<String, String>,
+    pub mirrors: HashMap<String, String>,
 }
 
 /// Application runtime context.