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-tauri/src/commands/invoice.rs

@@ -546,6 +546,83 @@ pub fn list_invoices_impl(conn: &Connection) -> Result<Vec<InvoiceSummary>, Stri
     Ok(rows)
 }
 
+/// What the History export needs beyond `InvoiceSummary`: the tax split and CA-facing fields, all money as
+/// integer paise. Joined to the list rows by `id` on the TypeScript side.
+#[derive(Debug, Clone, serde::Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct InvoiceLedgerRow {
+    pub id: i64,
+    pub client_gstin: String,
+    pub place_of_supply_code: String,
+    pub doc_type: String,
+    /// Distinct non-empty HSN/SAC codes of the lines, in line order.
+    pub hsn_sac: Vec<String>,
+    /// Subtotal less discount.
+    pub taxable_paise: i64,
+    pub cgst_paise: i64,
+    pub sgst_paise: i64,
+    pub igst_paise: i64,
+    pub reverse_charge: bool,
+}
+
+pub fn list_invoice_ledger_impl(conn: &Connection) -> Result<Vec<InvoiceLedgerRow>, String> {
+    let mut hsn_by_invoice: std::collections::HashMap<i64, Vec<String>> = std::collections::HashMap::new();
+    {
+        let mut stmt = conn
+            .prepare("SELECT invoice_id, TRIM(hsn_sac) FROM invoice_items ORDER BY invoice_id, sort_order, id")
+            .map_err(|e| e.to_string())?;
+        let items = stmt
+            .query_map([], |r| Ok((r.get::<_, i64>(0)?, r.get::<_, String>(1)?)))
+            .map_err(|e| e.to_string())?;
+        for item in items {
+            let (id, code) = item.map_err(|e| e.to_string())?;
+            let list = hsn_by_invoice.entry(id).or_default();
+            if !code.is_empty() && !list.contains(&code) {
+                list.push(code);
+            }
+        }
+    }
+    let mut stmt = conn
+        .prepare(
+            "SELECT id, client_gstin, place_of_supply_state_code, doc_type, subtotal, discount,
+                    cgst_amount, sgst_amount, igst_amount, reverse_charge
+             FROM invoices ORDER BY id DESC",
+        )
+        .map_err(|e| e.to_string())?;
+    let rows = stmt
+        .query_map([], |r| {
+            let id: i64 = r.get(0)?;
+            Ok(InvoiceLedgerRow {
+                id,
+                client_gstin: r.get(1)?,
+                place_of_supply_code: r.get(2)?,
+                doc_type: r.get(3)?,
+                hsn_sac: Vec::new(),
+                taxable_paise: gst::rupees_to_paise(r.get(4)?) - gst::rupees_to_paise(r.get(5)?),
+                cgst_paise: gst::rupees_to_paise(r.get(6)?),
+                sgst_paise: gst::rupees_to_paise(r.get(7)?),
+                igst_paise: gst::rupees_to_paise(r.get(8)?),
+                reverse_charge: r.get::<_, i64>(9)? != 0,
+            })
+        })
+        .map_err(|e| e.to_string())?
+        .collect::<rusqlite::Result<Vec<_>>>()
+        .map_err(|e| e.to_string())?;
+    Ok(rows
+        .into_iter()
+        .map(|mut row| {
+            row.hsn_sac = hsn_by_invoice.remove(&row.id).unwrap_or_default();
+            row
+        })
+        .collect())
+}
+
+#[tauri::command]
+pub fn list_invoice_ledger(state: State<AppState>) -> Result<Vec<InvoiceLedgerRow>, String> {
+    let conn = state.db.lock().map_err(|e| e.to_string())?;
+    list_invoice_ledger_impl(&conn)
+}
+
 pub fn get_invoice_impl(conn: &Connection, id: i64) -> Result<Invoice, String> {
     fetch_invoice(conn, id).map_err(|e| e.to_string())
 }
@@ -696,6 +773,28 @@ mod tests {
         conn.query_row("SELECT COUNT(*) FROM invoices", [], |r| r.get(0)).unwrap()
     }
 
+    #[test]
+    fn ledger_rows_carry_the_tax_split_in_paise_and_distinct_hsn() {
+        let mut conn = registered();
+        let first = issue(&mut conn, input(json!({"placeOfSupplyStateCode": "27"}))).unwrap();
+        conn.execute("UPDATE invoice_items SET hsn_sac = ' 9983 ' WHERE invoice_id = ?1", params![first.id]).unwrap();
+        conn.execute(
+            "INSERT INTO invoice_items (invoice_id, description, amount, sort_order, hsn_sac) VALUES (?1, 'b', 1, 5, '9983'), (?1, 'c', 1, 6, '9984'), (?1, 'd', 1, 7, '')",
+            params![first.id],
+        )
+        .unwrap();
+        let ledger = list_invoice_ledger_impl(&conn).unwrap();
+        assert_eq!(ledger.len(), 1);
+        let row = &ledger[0];
+        assert_eq!(row.id, first.id);
+        assert_eq!(row.place_of_supply_code, "27");
+        assert_eq!(row.doc_type, "tax_invoice");
+        assert_eq!(row.hsn_sac, vec!["9983".to_string(), "9984".to_string()]);
+        assert_eq!(row.taxable_paise, 731_000);
+        assert_eq!((row.cgst_paise, row.sgst_paise, row.igst_paise), (65_790, 65_790, 0));
+        assert!(!row.reverse_charge);
+    }
+
     #[test]
     fn issues_numbered_tax_invoices_with_derived_totals() {
         let mut conn = registered();