Add backup/restore, daily auto-backup and history CSV/JSON export (Phase E3)

- create_backup writes a zip (manifest with sha256 per file, a VACUUM INTO database snapshot, assets, archive, fonts) atomically. restore_backup validates the manifest, rejects tampered files, path traversal, symlinks and newer schemas, checks the staged DB with integrity_check, then stages a pending restore. The swap runs on the next start before the database opens, moves the current data to backups/pre-restore-<ts>/ and rolls back on any failure.
- Daily automatic backup (migration M9 auto_backup, default on) keeps the newest 14 and never blocks startup.
- Settings Data tab: back up now, restore with confirmation and restart, auto-backup toggle, last backup time.
- History exports the filtered rows as CSV (UTF-8 BOM, CRLF, formula-injection guard) or JSON (voiced.history.v1) with CA-friendly tax columns from a new list_invoice_ledger command.
- Rust round-trip, rejection, swap-rollback and retention tests; vitest for the export and backup helpers.

Adds the zip 8.6.0 and typed-path 0.12.3 crates (pure Rust); package builds must vendor them. PDF output and fingerprint goldens are unchanged. The new UI has not been run in a webview yet.

src/views/AppSettings.tsx

@@ -39,6 +39,7 @@ import {
 import { emailError, ifscError, panError, phoneError, vendorGstinError } from "../lib/validators";
 import { ImagePicker } from "../components/ImagePicker";
 import { LogoBranding } from "../components/LogoBranding";
+import DataBackupPanel from "../components/DataBackupPanel";
 import DiagnosticsPanel from "../components/DiagnosticsPanel";
 import { FontOverrideTable } from "../components/FontOverrideTable";
 import { useToast } from "../components/ToastProvider";
@@ -513,9 +514,7 @@ export default function AppSettings({
       </section>
             </TabPanel>
             <TabPanel>
-              <section className="voiced-stack">
-                <p>Backup and export arrive in the next step.</p>
-              </section>
+              <DataBackupPanel />
             </TabPanel>
         </TabPanels>
       </Tabs>