feat(core): wire up undo feature

espanso/src/cli/worker/config.rs

@@ -90,7 +90,7 @@ impl<'a> espanso_engine::process::MatchFilter for ConfigManager<'a> {
       .filter(|id| is_builtin_match(**id))
       .map(|id| *id)
       .collect();
-    
+
     let mut output = active_user_defined_matches;
     output.extend(builtin_matches);
     output
@@ -160,3 +160,9 @@ impl<'a> espanso_engine::process::MatcherMiddlewareConfigProvider for ConfigMana
     self.default().backspace_limit()
   }
 }
+
+impl<'a> espanso_engine::process::UndoEnabledProvider for ConfigManager<'a> {
+  fn is_undo_enabled(&self) -> bool {
+    self.active().undo_backspace()
+  }
+}

espanso/src/cli/worker/engine/mod.rs

@@ -188,6 +188,7 @@ pub fn initialize_and_spawn(
         disable_options,
         &config_manager,
         &combined_match_cache,
+        &config_manager,
       );
 
       let event_injector = EventInjectorAdapter::new(&*injector, &config_manager);

espanso/src/patch/patches/mod.rs

@@ -45,5 +45,6 @@ generate_patchable_config!(
   word_separators -> Vec<String>,
   backspace_limit -> usize,
   apply_patch -> bool,
+  undo_backspace -> bool,
   keyboard_layout -> Option<RMLVOConfig>
 );