Add PDF archive store, raw-body IPC and export file helpers

The searchable PDF can be archived content-addressed under the local data
dir with its sha256 and layout fingerprint; a different PDF for an archived
invoice is refused and reads verify the hash. Export writes go through a
raw-body command that remembers the last folder; reveal-in-folder and open
fall back to xdg-open / explorer. Adds a Windows-safe export file name
builder. Migration M4 adds the archive columns and last export dir.

src/lib/api.ts

@@ -10,6 +10,13 @@ import type {
   Settings,
 } from "./types";
 
+export interface ArchiveStatus {
+  archived: boolean;
+  sha256?: string;
+  fingerprint?: string;
+  archivedAt?: string;
+}
+
 export const api = {
   getSettings: () => invoke<Settings>("get_settings"),
   saveSettings: (settings: Settings) => invoke<Settings>("save_settings", { settings }),
@@ -47,6 +54,19 @@ export const api = {
     invoke<string>("save_asset_bytes", { kind, fileName, dataBase64 }),
   readAssetDataUri: (path: string) => invoke<string>("read_asset_data_uri", { path }),
   removeAsset: (path: string) => invoke<void>("remove_asset", { path }),
-  saveBinaryFile: (path: string, dataBase64: string) =>
-    invoke<void>("save_binary_file", { path, dataBase64 }),
+
+  // Raw-body commands: the payload is the bytes themselves (no base64); metadata goes in headers.
+  // Header values must be visible ASCII, hence the encodeURIComponent on paths.
+  archivePdf: (invoiceId: number, bytes: Uint8Array, fingerprint: string) =>
+    invoke<string>("archive_pdf", bytes, {
+      headers: { "x-invoice-id": String(invoiceId), "x-fingerprint": fingerprint },
+    }),
+  readArchive: async (invoiceId: number): Promise<Uint8Array> =>
+    new Uint8Array(await invoke<ArrayBuffer>("read_archive", { invoiceId })),
+  archiveStatus: (invoiceId: number) => invoke<ArchiveStatus>("archive_status", { invoiceId }),
+  writeExportFile: (path: string, bytes: Uint8Array) =>
+    invoke<string>("write_export_file", bytes, { headers: { "x-path": encodeURIComponent(path) } }),
+  getLastExportDir: () => invoke<string>("get_last_export_dir"),
+  revealInFolder: (path: string) => invoke<void>("reveal_in_folder", { path }),
+  openFile: (path: string) => invoke<void>("open_file", { path }),
 };