Switch order/verification email From to sellerEmail's domain, honor emailFromName/emailFromAddress override

Mirrors the backend's sellerInfo.ts buildFromHeader() change — SMTP
account moved to admin@einfach-produktiv.com, so From can finally point
at sellerEmail itself instead of the fixed admin@mk360.de placeholder.

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

app/company-settings-preview/page.tsx

@@ -21,6 +21,8 @@ const FALLBACK: CompanySettings = {
   sellerCity: "",
   sellerCountry: "",
   sellerEmail: "",
+  emailFromName: null,
+  emailFromAddress: null,
   vatId: "",
   taxRatePercent: 19,
   kleinunternehmer: false,

app/lib/alertAdmin.ts

@@ -40,10 +40,10 @@ export async function sendVerificationEmail(to: string, firstName: string, token
   const url = `https://einfach-produktiv.mk360.de/api/account/verify-email?token=${token}`;
   const seller = await getSellerForInvoice();
   await transport.sendMail({
-    // See orderEmail.ts's own comment on why only the display name is
-    // dynamic — the address stays admin@mk360.de until sellerEmail's domain
-    // is confirmed SPF-authorized on the Hostinger account.
-    from: `"${seller?.sellerName ?? "einfach produktiv"}" <admin@mk360.de>`,
+    // See orderEmail.ts's own comment — From now matches sellerEmail
+    // itself since the SMTP account moved to a mailbox on that domain,
+    // and emailFromName/emailFromAddress let an admin override both.
+    from: `"${seller?.emailFromName || seller?.sellerName || "Björn"}" <${seller?.emailFromAddress || seller?.sellerEmail || "hallo@einfach-produktiv.com"}>`,
     replyTo: seller?.sellerEmail || undefined,
     to,
     subject: "Bitte bestätige deine E-Mail-Adresse",

app/lib/orderEmail.ts

@@ -129,12 +129,16 @@ export async function sendOrderConfirmationEmail(order: OrderConfirmationEmailDa
   }
 
   await transport.sendMail({
-    // Display name only, not the address — see the memory note on why the
-    // envelope stays admin@mk360.de (that's the domain the Hostinger SMTP
-    // account is actually authorized for; sellerEmail's domain isn't
-    // confirmed SPF-authorized on it yet). Reply-To is what actually routes
-    // a customer's reply to the seller, regardless of the From address.
-    from: `"${seller?.sellerName ?? "einfach produktiv"}" <admin@mk360.de>`,
+    // SPF confirmed 2026-07-29 for einfach-produktiv.com, and the SMTP
+    // account itself switched to a mailbox on that domain — see the
+    // backend's sellerInfo.ts buildFromHeader() comment for why both had
+    // to move together (Hostinger's relay rejects a From address the
+    // authenticated mailbox doesn't own). Reply-To stays set too, though
+    // now redundant with From itself pointing at sellerEmail.
+    // emailFromName/emailFromAddress (company-settings) are the
+    // admin-editable override, same fallback chain as the backend's
+    // buildFromHeader().
+    from: `"${seller?.emailFromName || seller?.sellerName || "Björn"}" <${seller?.emailFromAddress || seller?.sellerEmail || "hallo@einfach-produktiv.com"}>`,
     replyTo: seller?.sellerEmail || undefined,
     to: customerEmail,
     subject: template.subject,

app/lib/payload.ts

@@ -878,6 +878,12 @@ export type CompanySettings = {
   sellerCity: string;
   sellerCountry: string;
   sellerEmail: string;
+  // Admin-editable override for outgoing mail's "Von"-Feld (company-settings
+  // "Adresse & Kontakt" tab, added 2026-07-29 alongside the SPF/SMTP-account
+  // switch to einfach-produktiv.com) — falls back to sellerName/sellerEmail
+  // when empty, see orderEmail.ts/alertAdmin.ts's own comments.
+  emailFromName: string | null;
+  emailFromAddress: string | null;
   vatId: string;
   taxRatePercent: number;
   // Kleinunternehmerregelung (§19 UStG) — when true, checkout forces every