Merge pull request #460 from llopjulen/i18n/es

Ported onto the current language plumbing next to Ukrainian (catalog
codes, Match System, native menu Services label, docs, tests), and the
stale Ease Presets row (a ScriptUI panel since #404) dropped.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QiAJeFttZp83Fh7YuzAR5f

crates/engine/src/prefs.rs

@@ -23,8 +23,15 @@ pub const PREFS_VERSION: u32 = 2;
 pub const PREFS_FILE: &str = "prefs.json";
 
 /// Settings ▸ General ▸ Language: (label, `general.language` value).
-pub const LANGUAGES: &[(&str, &str)] =
-    &[("Match System", "system"), ("English", "en"), ("日本語", "ja"), ("简体中文", "zh-hans"), ("繁體中文", "zh-hant"), ("Українська", "uk")];
+pub const LANGUAGES: &[(&str, &str)] = &[
+    ("Match System", "system"),
+    ("English", "en"),
+    ("日本語", "ja"),
+    ("简体中文", "zh-hans"),
+    ("繁體中文", "zh-hant"),
+    ("Українська", "uk"),
+    ("Español", "es"),
+];
 
 /// Settings ▸ Appearance ▸ UI Scale: (label, `appearance.uiScale` percent).
 pub const UI_SCALES: &[(&str, &str)] = &[("75%", "75"), ("100%", "100"), ("125%", "125"), ("150%", "150"), ("175%", "175"), ("200%", "200")];

crates/engine/src/tests_settings.rs

@@ -606,6 +606,11 @@ fn interface_language_is_validated_persisted_and_backward_compatible() {
     uk.load_settings();
     assert_eq!(uk.prefs.general.language, "uk");
     assert_eq!(Prefs::from_json(r#"{"general":{"language":"uk"}}"#).general.language, "uk");
+    // es is registered the same way.
+    s.execute("prefs.set", json!({"key": "general.language", "value": "es"})).unwrap();
+    let mut es = Session { config: Some(store.clone()), ..Default::default() };
+    es.load_settings();
+    assert_eq!(es.prefs.general.language, "es");
     s.execute("prefs.set", json!({"key": "general.language", "value": "ja"})).unwrap();
     let mut reloaded = Session { config: Some(store), ..Default::default() };
     reloaded.load_settings();