feat: add local OneNote and ONEPKG reader

src/source-file.ts

@@ -0,0 +1,10 @@
+import type { SourceKind } from './worker/onenote.client.js';
+
+export const MAX_SOURCE_FILE_BYTES = 512 * 1024 * 1024;
+
+export function sourceKindFromFileName(fileName: string): SourceKind | null {
+  const normalized = fileName.toLocaleLowerCase('en-US');
+  if (normalized.endsWith('.onepkg')) return 'onepkg';
+  if (normalized.endsWith('.one')) return 'one';
+  return null;
+}