feat: migrate Milkdown integration to local vendor bundle model

src/NexusReader.UI.Shared/wwwroot/js/milkdownWrapper.js

@@ -1,20 +1,20 @@
 // Map to keep track of active Crepe editor instances by elementId (container ID)
-const editors = new Map();
+const editorCache = new Map();
 
 /**
  * Asynchronously injects a stylesheet link tag into the document head
  * and returns a Promise that resolves when the stylesheet is fully loaded.
  */
-async function injectStylesheet(url) {
-    if (document.querySelector(`link[href="${url}"]`)) {
+async function ensureStylesheet(href) {
+    if (document.querySelector(`link[href="${href}"]`)) {
         return Promise.resolve();
     }
     return new Promise((resolve, reject) => {
         const link = document.createElement('link');
         link.rel = 'stylesheet';
-        link.href = url;
+        link.href = href;
         link.onload = () => resolve();
-        link.onerror = (err) => reject(new Error(`Failed to load stylesheet: ${url}. ${err}`));
+        link.onerror = (err) => reject(new Error(`Failed to load stylesheet: ${href}. ${err}`));
         document.head.appendChild(link);
     });
 }
@@ -31,13 +31,16 @@ export async function initEditor(elementId, dotNetHelper, initialMarkdown) {
 
     try {
         // Condition 2: Prevent FOUC by loading stylesheets before instantiating the editor
-        await Promise.all([
-            injectStylesheet('https://esm.sh/@milkdown/crepe/lib/theme/common/style.css'),
-            injectStylesheet('https://esm.sh/@milkdown/crepe/lib/theme/frame/style.css')
-        ]);
+        await ensureStylesheet('/_content/NexusReader.UI.Shared/css/vendor/milkdown-crepe.css');
 
-        // Dynamically import the Crepe ESM module
-        const { Crepe } = await import('https://esm.sh/@milkdown/crepe');
+        // Dynamically import the local JS bundle
+        await import('/_content/NexusReader.UI.Shared/js/vendor/milkdown-crepe.js');
+
+        // Get Crepe constructor from the global window.milkdownCrepe namespace
+        const Crepe = window.milkdownCrepe?.Crepe;
+        if (!Crepe) {
+            throw new Error("Crepe constructor not found on window.milkdownCrepe");
+        }
 
         // Initialize the Crepe editor instance with custom ImageBlock upload handler
         const crepe = new Crepe({
@@ -61,7 +64,7 @@ export async function initEditor(elementId, dotNetHelper, initialMarkdown) {
         });
 
         // Store the editor instance in the map
-        editors.set(elementId, crepe);
+        editorCache.set(elementId, crepe);
 
         // Create the editor view asynchronously
         await crepe.create();
@@ -76,7 +79,7 @@ export async function initEditor(elementId, dotNetHelper, initialMarkdown) {
  * Retrieves the current Markdown content from a specific editor instance.
  */
 export function getMarkdownContent(elementId) {
-    const crepe = editors.get(elementId);
+    const crepe = editorCache.get(elementId);
     if (!crepe) {
         console.warn(`[Milkdown] No editor instance found for element: ${elementId}`);
         return "";
@@ -88,7 +91,7 @@ export function getMarkdownContent(elementId) {
  * Safely disposes of the editor instance to prevent memory leaks in WASM.
  */
 export async function destroyEditor(elementId) {
-    const crepe = editors.get(elementId);
+    const crepe = editorCache.get(elementId);
     if (crepe) {
         try {
             await crepe.destroy();
@@ -96,6 +99,6 @@ export async function destroyEditor(elementId) {
         } catch (error) {
             console.error(`[Milkdown] Error destroying editor for element "${elementId}":`, error);
         }
-        editors.delete(elementId);
+        editorCache.delete(elementId);
     }
 }