Add legalForm-driven Pflichtangaben (register court/number, managing director)

Mirrors the Payload backend's new company-settings.legalForm field: when
present, registerCourt/registerNumber/managingDirector now appear in the
email footer (buildLegalFooterLines) and both invoice PDF footers,
matching §37a HGB / §35a GmbHG requirements for registered legal forms.
A sole proprietorship (the default) renders identically to before —
these fields are only appended when actually set.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/payload.ts

@@ -645,6 +645,13 @@ export async function getEmailTemplate(
 
 export type CompanySettings = {
   sellerName: string;
+  // Drives whether registerCourt/registerNumber/managingDirector are
+  // populated — mirrors Payload's CompanySettings.ts collection exactly
+  // (same option values), see buildLegalFooterLines() in emailTemplates.ts.
+  legalForm: "sole-proprietorship" | "e-k" | "gbr" | "ohg" | "kg" | "gmbh" | "ug" | "ag";
+  registerCourt: string | null;
+  registerNumber: string | null;
+  managingDirector: string | null;
   sellerStreet: string;
   sellerZip: string;
   sellerCity: string;