Add the ERPNext settings UI, History and detail controls, and voiced.invoice.v1 export (Phase F3)

- Settings gets an Integrations tab: connection fields with a write-only API secret, a CA PEM option, Test connection with versions and warnings, live mapping lists loaded after a test, naming mode, toggles and its own Save.
- Pushing for a GST-registered vendor is refused until a connection test result is stored. The UI shows the reason and disables Send.
- History shows an ERPNext status column from one bulk call, a row Send and Open in ERPNext, and a bulk Send selected with a draft-or-submit confirm step and per-row results that never abort the batch. The detail view gets an ERPNext panel and per-payment send. All of it is hidden or disabled when the integration is not configured.
- Optional auto-push after issue runs in the background and never blocks or fails the issue.
- Generic export: a deterministic voiced.invoice.v1 JSON (and CSV line items) for selected invoices, documented in docs/voiced-invoice-v1.md with a golden test. Money is integer paise plus a decimal string.

The new screens have not been run in a webview yet. The ERPNext Payment Entry deduction fields still need a live check.

src-tauri/src/integrations/erpnext/push.rs

@@ -323,6 +323,14 @@ fn load_item_codes(conn: &Connection, inv: &Invoice) -> Result<Vec<Option<String
     Ok(inv.items.iter().map(|i| by_desc.get(&i.description.trim().to_lowercase()).cloned()).collect())
 }
 
+/// True when a connection test result is stored (blank, `null` and `{}` count as none).
+fn has_detect_result(raw: &str) -> bool {
+    match serde_json::from_str::<Value>(raw) {
+        Ok(Value::Object(m)) => !m.is_empty(),
+        _ => false,
+    }
+}
+
 fn load_for_push(db: &Db, local_dir: &Path, invoice_id: i64) -> Result<Loaded, (String, ErpError)> {
     let conn = db
         .lock()
@@ -346,6 +354,11 @@ fn load_for_push(db: &Db, local_dir: &Path, invoice_id: i64) -> Result<Loaded, (
     let cfg = config::load(&conn).map_err(|e| fail(pre(e)))?;
     let vendor = Vendor::from_snapshot(&invoice.vendor_snapshot)
         .ok_or_else(|| fail(pre(format!("Invoice {number} has no supplier details recorded, so it cannot be sent."))))?;
+    // A registered vendor's invoices go out with India Compliance fields, and those depend on what the
+    // connection test detected, so refuse until the test has run once.
+    if vendor.registered && !has_detect_result(&cfg.last_detect_result) {
+        return Err(fail(pre("Run Test connection first (Settings, Integrations): Voiced has not yet checked this ERPNext site.")));
+    }
     let client = load_client(&conn, &invoice).map_err(|e| fail(pre(e)))?;
     let item_codes = load_item_codes(&conn, &invoice).map_err(|e| fail(pre(e)))?;
     let sync = load_sync(&conn, invoice_id).map_err(|e| fail(pre(e)))?;

src-tauri/src/integrations/erpnext/push/tests.rs

@@ -518,6 +518,45 @@ async fn cancelled_and_draft_invoices_are_refused_before_any_request() {
     assert!(fx.sync_row(inv.id).is_none() && fx.sync_row(draft_id).is_none());
 }
 
+#[tokio::test]
+async fn a_registered_vendor_must_run_the_connection_test_before_pushing() {
+    let fx = Fx::new(|c| c.last_detect_result = String::new());
+    let inv = fx.issue("Client Ltd");
+    let mut routes = master_routes();
+    routes.push(mirror_create(&inv.number, 0, inv.total));
+    let m = mock(routes).await;
+
+    let r = fx.push(&m, inv.id, Some(false)).await;
+    assert!(!r.ok && r.status == "refused" && r.error_kind == Some(ErrorKind::Precondition), "{r:?}");
+    assert!(r.error.as_deref().unwrap().contains("Run Test connection first"), "{r:?}");
+    assert!(m.requests.lock().unwrap().is_empty());
+    assert!(fx.sync_row(inv.id).is_none());
+
+    // `{}` and `null` are as good as nothing; a stored result unlocks the push.
+    assert!(!has_detect_result("") && !has_detect_result("{}") && !has_detect_result("null"));
+    fx.db.lock().unwrap().execute("UPDATE erpnext_config SET last_detect_result = '{\"indiaCompliance\":false}'", []).unwrap();
+    let r = fx.push(&m, inv.id, Some(false)).await;
+    assert!(r.ok, "{r:?}");
+}
+
+#[tokio::test]
+async fn an_unregistered_vendor_needs_no_connection_test() {
+    let fx = Fx::new(|c| c.last_detect_result = String::new());
+    let inv = fx.issue("Other Co");
+    // Only the frozen supplier snapshot decides whether the invoice counts as a registered vendor's.
+    fx.db
+        .lock()
+        .unwrap()
+        .execute("UPDATE invoices SET vendor_snapshot = replace(vendor_snapshot, '\"gstRegistration\":\"regular\"', '\"gstRegistration\":\"unregistered\"')", [])
+        .unwrap();
+    assert!(!Vendor::from_snapshot(&get_invoice_impl(&fx.db.lock().unwrap(), inv.id).unwrap().vendor_snapshot).unwrap().registered);
+    let mut routes = master_routes();
+    routes.push(mirror_create(&inv.number, 0, inv.total));
+    let m = mock(routes).await;
+    let r = fx.push(&m, inv.id, Some(false)).await;
+    assert!(r.status != "refused", "{r:?}");
+}
+
 #[tokio::test]
 async fn an_unarchived_invoice_is_pushed_without_a_pdf_and_attached_by_a_later_push() {
     let fx = Fx::new(|_| {});