feat: add unlock icon and update layer lock UI, and fix document loading index management and cache synchronization

hcie-iced-app/assets/icons/unlock.svg

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" fill="currentColor">
+  <g transform="translate(40.96,40.96) scale(17.920000) translate(-0.00,-0.00)">
+    <path d="M18 10h-7V7c0-1.7 1.4-3.1 3.1-3.1 1.7 0 3.1 1.4 3.1 3.1h2c0-2.8-2.2-5-5-5S7 4.2 7 7v3H6c-1.1 0-2 .9-2 2v8c0 1.1.9 2 2 2h12c1.1 0 2-.9 2-2v-8c0-1.1-.9-2-2-2zm-6 9c-1.1 0-2-.9-2-2s.9-2 2-2 2 .9 2 2-.9 2-2 2z"/>
+  </g>
+</svg>

hcie-iced-app/crates/hcie-iced-gui/src/app.rs

@@ -3591,6 +3591,8 @@ impl HcieIcedApp {
                     .engine
                     .set_layer_locked(id, locked);
                 self.documents[self.active_doc].modified = true;
+                self.documents[self.active_doc].cached_layers =
+                    self.documents[self.active_doc].engine.layer_infos();
             }
 
             Message::LayerSetOpacity(id, opacity) => {
@@ -7838,7 +7840,9 @@ impl HcieIcedApp {
 
                 match self.pending_file_operation.take() {
                     Some(PendingFileOperation::Open) => {
-                        let engine = &mut self.documents[self.active_doc].engine;
+                        let _ = self.update(Message::NewDocument(1, 1));
+                        let doc_idx = self.documents.len() - 1;
+                        let engine = &mut self.documents[doc_idx].engine;
                         let result = match ext.as_str() {
                             "psd" => engine.import_psd(&path_str),
                             "kra" => engine.import_kra(&path_str),
@@ -7848,20 +7852,30 @@ impl HcieIcedApp {
                         match result {
                             Ok(()) => {
                                 self.show_welcome = false;
-                                self.documents[self.active_doc].engine.pre_tile_all_layers();
+                                self.active_doc = doc_idx;
-                                self.documents[self.active_doc].selection_model_dirty = true;
+                                self.documents[doc_idx].engine.pre_tile_all_layers();
-                                self.documents[self.active_doc].name = path
+                                self.documents[doc_idx].selection_model_dirty = true;
+                                self.documents[doc_idx].name = path
                                     .file_name()
                                     .map(|n| n.to_string_lossy().to_string())
                                     .unwrap_or_else(|| "Untitled".to_string());
-                                self.documents[self.active_doc].source_path = Some(path.clone());
+                                self.documents[doc_idx].source_path = Some(path.clone());
-                                self.documents[self.active_doc].modified = false;
+                                self.documents[doc_idx].modified = false;
                                 self.add_recent_file(&path);
-                                self.documents[self.active_doc].full_upload.replace(true);
+                                self.documents[doc_idx].full_upload.replace(true);
+                                self.documents[doc_idx].cached_layers =
+                                    self.documents[doc_idx].engine.layer_infos();
                                 self.refresh_composite_if_needed();
                                 return Task::perform(async {}, |_| Message::CompositeRefresh);
                             }
-                            Err(e) => log::error!("Failed to open: {}", e),
+                            Err(e) => {
+                                log::error!("Failed to open: {}", e);
+                                // Remove empty dummy document if load failed
+                                if self.documents.len() > 1 {
+                                    self.documents.pop();
+                                    self.active_doc = self.documents.len() - 1;
+                                }
+                            }
                         }
                     }
                     Some(PendingFileOperation::SaveAs { close_after }) => {

hcie-iced-app/crates/hcie-iced-gui/src/panels/layers.rs

@@ -339,8 +339,13 @@ pub fn view<'a>(
             14.0,
         );
 
+        let lock_icon_path = if info.locked {
+            "icons/lock.svg"
+        } else {
+            "icons/unlock.svg"
+        };
         let row_lock = svg_icon_btn(
-            "icons/lock.svg",
+            lock_icon_path,
             if info.locked { "Unlock" } else { "Lock" },
             Message::LayerToggleLock(info.id),
             colors,