Add 'Save Image As...' to context menu and image saving support

Introduces a 'Save Image As...' option to the context menu for images. Implements IPC handlers in main and preload scripts to save images from URLs, data URLs, and file URLs. Updates renderer logic to handle saving images from various sources, including blob URLs via webview conversion.

main.js

@@ -643,6 +643,7 @@ function buildAndShowContextMenu(sender, params = {}) {
       template.push(
         { label: 'Open Image in New Tab', click: () => embedder.send('context-menu-command', { cmd: 'open-image-new-tab', url: imageURL }) },
         { label: 'Copy Image Address', click: () => clipboard.writeText(imageURL) },
+  { label: 'Save Image As...', click: () => embedder.send('context-menu-command', { cmd: 'save-image', url: imageURL, mime: params.mediaType === 'image' ? params.mimeType : undefined }) },
         { type: 'separator' }
       );
     }
@@ -688,3 +689,59 @@ app.on('web-contents-created', (event, contents) => {
     buildAndShowContextMenu(contents, params);
   });
 });
+
+// --- Image save handlers ---
+ipcMain.handle('save-image-from-dataurl', async (event, { suggestedName = 'image', dataUrl }) => {
+  try {
+    if (!dataUrl || !dataUrl.startsWith('data:')) return false;
+    const match = /^data:(.*?);base64,(.*)$/.exec(dataUrl);
+    if (!match) return false;
+    const mime = match[1] || 'application/octet-stream';
+    const ext = (mime.split('/')[1] || 'png').split(';')[0];
+    const buf = Buffer.from(match[2], 'base64');
+    const win = BrowserWindow.fromWebContents(event.sender.hostWebContents || event.sender);
+    const { canceled, filePath } = await dialog.showSaveDialog(win, { defaultPath: `${suggestedName}.${ext}` });
+    if (canceled || !filePath) return false;
+    await fs.promises.writeFile(filePath, buf);
+    return true;
+  } catch (err) {
+    console.error('save-image-from-dataurl failed:', err);
+    return false;
+  }
+});
+
+ipcMain.handle('save-image-from-url', async (event, { url }) => {
+  if (!url) return false;
+  const win = BrowserWindow.fromWebContents(event.sender.hostWebContents || event.sender);
+  try {
+    let dataBuf;
+    if (url.startsWith('http')) {
+      const res = await fetch(url);
+      if (!res.ok) throw new Error('HTTP '+res.status);
+      const arrayBuf = await res.arrayBuffer();
+      dataBuf = Buffer.from(arrayBuf);
+      const ctype = res.headers.get('content-type') || 'application/octet-stream';
+      const ext = (ctype.split('/')[1] || 'png').split(';')[0];
+      const { canceled, filePath } = await dialog.showSaveDialog(win, { defaultPath: `image.${ext}` });
+      if (canceled || !filePath) return false;
+      await fs.promises.writeFile(filePath, dataBuf);
+      return true;
+    } else if (url.startsWith('data:')) {
+      // Forward to dataURL handler path – easier to keep logic single
+      return ipcMain.emit('save-image-from-dataurl', event, { dataUrl: url });
+    } else if (url.startsWith('file:')) {
+      // Copy file to chosen destination
+      const filePathSrc = new URL(url).pathname.replace(/^\//, '');
+      const base = path.basename(filePathSrc);
+      const { canceled, filePath } = await dialog.showSaveDialog(win, { defaultPath: base });
+      if (canceled || !filePath) return false;
+      await fs.promises.copyFile(filePathSrc, filePath);
+      return true;
+    } else {
+      return false;
+    }
+  } catch (err) {
+    console.error('save-image-from-url failed:', err);
+    return false;
+  }
+});