feat: enhance backup and download functionalities

- Updated `BackupCenterPage` to support download progress tracking during remote backup downloads.
- Modified `ImportPage` to simplify export functionality by removing unnecessary payload handling.
- Improved `JwtWarningPage` to utilize a new clipboard utility for copying text with feedback.
- Enhanced `PublicSendPage` to show download progress for files being downloaded.
- Updated `RecoverTwoFactorPage` to include autocomplete attributes for better user experience.
- Refactored `SendsPage` to use the new clipboard utility for copying access URLs.
- Enhanced `SettingsPage` to utilize the clipboard utility for copying sensitive information.
- Improved `TotpCodesPage` to use the clipboard utility for copying TOTP codes.
- Updated `VaultPage` and related components to support download progress for attachments.
- Introduced a new `app-notify` module for consistent notification handling across the application.
- Created a `clipboard` utility for improved clipboard interactions with user feedback.
- Added progress tracking for file downloads in the API layer, enhancing user experience during downloads.

webapp/src/lib/download.ts

@@ -10,3 +10,61 @@ export function downloadBytesAsFile(bytes: Uint8Array, fileName: string, mimeTyp
   anchor.remove();
   window.setTimeout(() => URL.revokeObjectURL(objectUrl), 0);
 }
+
+export interface DownloadProgressState {
+  loaded: number;
+  total: number | null;
+  percent: number | null;
+}
+
+type ProgressCallback = (progress: DownloadProgressState) => void;
+
+function parseContentLength(response: Response): number | null {
+  const raw = String(response.headers.get('Content-Length') || '').trim();
+  if (!raw) return null;
+  const parsed = Number(raw);
+  return Number.isFinite(parsed) && parsed > 0 ? parsed : null;
+}
+
+export async function readResponseBytesWithProgress(
+  response: Response,
+  onProgress?: ProgressCallback
+): Promise<Uint8Array> {
+  const total = parseContentLength(response);
+  const report = (loaded: number) => {
+    onProgress?.({
+      loaded,
+      total,
+      percent: total ? Math.max(0, Math.min(100, Math.round((loaded / total) * 100))) : null,
+    });
+  };
+
+  if (!response.body) {
+    const bytes = new Uint8Array(await response.arrayBuffer());
+    report(bytes.byteLength);
+    return bytes;
+  }
+
+  const reader = response.body.getReader();
+  const chunks: Uint8Array[] = [];
+  let loaded = 0;
+  report(0);
+
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    if (!value) continue;
+    chunks.push(value);
+    loaded += value.byteLength;
+    report(loaded);
+  }
+
+  const bytes = new Uint8Array(loaded);
+  let offset = 0;
+  for (const chunk of chunks) {
+    bytes.set(chunk, offset);
+    offset += chunk.byteLength;
+  }
+  report(loaded);
+  return bytes;
+}