Emit invoices as validated ZUGFeRD (DATEV) and XRechnung (B2G)

Completes the eRechnung output path: finalized invoices are emitted as a
ZUGFeRD/Factur-X EN 16931 hybrid (DATEV) or, when a Leitweg-ID is present, as
XRechnung 3.0 for B2G. Both are externally validated as ACCEPTED (0 errors) and
PDF/A-3B COMPLIANT against the ProcessWeb eInvoice service.

- ERechnungMapper: FdsInvoiceData -> EN 16931 model. Seller master data now from
  Fuchs:ERechnung:Seller config (VAT id BT-31, Steuernummer BT-32, optional
  Handelsregister BT-30, IBAN/BIC, contact). Adds payment terms BT-20/BT-9
  (BR-CO-25), buyer VAT id, §13b reverse charge, and the service date/period
  (BT-72 / BG-14) parsed from ProvisionPeriod (BR-DE-TMP-32). B2G -> XRechnung
  profile with the required electronic addresses/contact.
- ERechnungValidator: client for POST /validatepdf (EN 16931 XML + PDF/A-3 in
  one call). A pure "scenario not matched" with zero errors is not treated as a
  hard failure; real errors optionally withhold the hybrid (FailOnError).
- ERechnungSettings: seller + validation config; wired in Program.cs; ServiceUrl
  in appsettings.
- Online editor: structured German-only dialogs for the recipient address
  (incl. Leitweg-ID) and the service date/period (single date or range).
- Bumps the eRechnungLib submodule to the CII rsm-namespace / PDF-A subtype fix.

Fuchs.Tests 514/514, eRechnungLib 97/97.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Fuchs/wwwroot/web/fis.inv.de.js

@@ -1569,12 +1569,14 @@ $inv.eAddress = function (ev) {
         { name: 'postalCode', label: 'PLZ', type: 'text', value: cur.postalCode || '' },
         { name: 'city', label: 'Ort', type: 'text', value: cur.city || '' },
         { name: 'countryCode', label: 'Land', type: 'select', url: $inv.adrCountries, value: (cur.countryCode || 'DE') },
-        { name: 'vatId', label: 'USt-IdNr. (nur bei Firmen)', type: 'text', value: cur.vatId || '' }
+        { name: 'vatId', label: 'USt-IdNr. (nur bei Firmen)', type: 'text', value: cur.vatId || '' },
+        { name: 'leitwegId', label: 'Leitweg-ID (nur Behörden / B2G)', type: 'text', value: cur.leitwegId || '' }
     ];
     let hint = $$.dc('adr-conformity').append([
         $$.dc('hd').text('Hinweis zur DATEV-/eRechnungs-Konformität'),
         $$.dc('tx').text('Pflicht: Name, Straße, PLZ, Ort und Land. Die USt-IdNr. nur bei Firmen angeben — '
-            + 'für eine Rechnung an eine Privatperson einfach leer lassen.')
+            + 'für eine Rechnung an eine Privatperson einfach leer lassen. Eine Leitweg-ID nur bei '
+            + 'Behörden (B2G) — dann wird die Rechnung automatisch als XRechnung erzeugt.')
     ]);
     $ocms.dlgform(flds, {
         title: 'Rechnungsempfänger',
@@ -1583,7 +1585,8 @@ $inv.eAddress = function (ev) {
             let a = {
                 name: res.name || '', contact: res.contact || '', line2: res.line2 || '',
                 street: res.street || '', postalCode: res.postalCode || '', city: res.city || '',
-                countryCode: (res.countryCode || 'DE'), vatId: ('' + (res.vatId || '')).trim()
+                countryCode: (res.countryCode || 'DE'), vatId: ('' + (res.vatId || '')).trim(),
+                leitwegId: ('' + (res.leitwegId || '')).trim()
             };
             let txt = $inv.composeAddress(a);
             if (ev.data && ev.data.t) { ev.data.t.rwText(txt); }
@@ -1594,12 +1597,46 @@ $inv.eAddress = function (ev) {
     });
 };
 
+/* Leistungsdatum / -zeitraum: structured German-date entry only (no free text). A single date =
+   Leistungsdatum (BT-72); a from+to date = Leistungszeitraum (BG-14). The composed value is a
+   German dd.MM.yyyy string ("18.06.2026" or "01.06.2026 - 30.06.2026") that the PDF shows and the
+   backend maps to the eRechnung service date/period. */
+$inv.provToIso = function (dmy) {
+    let m = ('' + (dmy || '')).match(/(\d{1,2})\.(\d{1,2})\.(\d{4})/);
+    return m ? (m[3] + '-' + ('0' + m[2]).slice(-2) + '-' + ('0' + m[1]).slice(-2)) : '';
+};
+$inv.eProvisionPeriod = function (ev) {
+    let cur = ('' + (ev.data && ev.data.t ? ev.data.t.text() : '')).trim();
+    let dates = cur.match(/\d{1,2}\.\d{1,2}\.\d{4}/g) || [];
+    let flds = [
+        { name: 'von', label: 'Leistungsdatum', type: 'date', value: $inv.provToIso(dates[0] || '') },
+        { name: 'bis', label: 'Leistungszeitraum – bis (optional)', type: 'date', value: $inv.provToIso(dates[1] || '') }
+    ];
+    let hint = $$.dc('adr-conformity').append([
+        $$.dc('hd').text('Leistungsdatum / -zeitraum'),
+        $$.dc('tx').text('Für ein einzelnes Datum nur „Leistungsdatum" ausfüllen; für einen Zeitraum '
+            + 'zusätzlich das Bis-Datum. Nur strukturierte Datumsauswahl — für die E-Rechnung empfohlen.')
+    ]);
+    $ocms.dlgform(flds, {
+        title: 'Leistungsdatum / -zeitraum',
+        addcontent: hint,
+        success: function (res) {
+            let v = ('' + (res.von || '')).trim(), b = ('' + (res.bis || '')).trim();
+            let txt = v === '' ? '' : ((b === '' || b === v) ? v : (v + ' - ' + b));
+            if (ev.data && ev.data.t) { ev.data.t.rwText(txt); }
+            if (typeof (ev.data || {}).change === 'function') { ev.data.change(txt); }
+            $inv.d.sync({ Target: 'provisionperiod', Value: txt });
+        }
+    });
+};
+
 $inv.eHtml = function (ev) {
-    /* The recipient address is edited through the structured dialog whenever an invoice draft is
-       active; reminders (no invoice draft token) keep the plain free-text editor. */
-    if (ev.data && !(ev.data instanceof jQuery) && ev.data.nme === 'invoiceaddress'
-        && $inv.d && typeof $inv.d.token === 'function' && $inv.d.token() !== '') {
-        return $inv.eAddress.call(this, ev);
+    /* The recipient address and the service date/period are edited through structured dialogs
+       whenever an invoice draft is active; reminders (no invoice draft token) keep the plain
+       free-text editor. */
+    if (ev.data && !(ev.data instanceof jQuery) && $inv.d && typeof $inv.d.token === 'function' && $inv.d.token() !== '') {
+        if (ev.data.nme === 'invoiceaddress') { return $inv.eAddress.call(this, ev); }
+        if (ev.data.nme === 'provisionperiod') { return $inv.eProvisionPeriod.call(this, ev); }
     }
     let t = $(this), frmct = ev.data instanceof jQuery ? ev.data : ev.data.t;
     /* Single-line fields must stay plain text — the TinyMCE/html editor wraps the value in <p>