Fix: localize reply/forward quote header incl. sender address

The reply/forward quote header was always emitted in English ("On {date},
{from} wrote:", "---------- Forwarded message ----------", From/Date/Subject)
regardless of UI language, in both the main path (lib/quote-header.ts) and the
composer's inline fallback. quote-header.ts now takes an optional localized
QuoteHeaderLabels set (English defaults preserved for back-compat); page.tsx
builds it from a new quote_header message namespace, and the composer fallback
uses the same keys. Added the quote_header namespace to all 17 locales.

Also folds in the forward-sender-address fix: the forward "From:" line now
shows the full "Name <email>" like every mail client (the reply line keeps the
bare name, which reads naturally in "On … wrote:").

lib/quote-header.ts

@@ -10,6 +10,17 @@ import { formatDateTime } from "@/lib/utils";
 import { emailHooks } from "@/lib/plugin-hooks";
 import type { QuoteHeader, QuoteHeaderContext } from "@/lib/plugin-types";
 
+// Localized label set the caller passes in. Labels live on the client where
+// useTranslations is available; this module stays framework-agnostic.
+export interface QuoteHeaderLabels {
+  /** ICU-formatted reply line, e.g. "On {date}, {from} wrote:" with placeholders already substituted. */
+  formatReplyLine: (vars: { date: string; from: string }) => string;
+  forwardedSeparator: string;
+  fromLabel: string;
+  dateLabel: string;
+  subjectLabel: string;
+}
+
 interface BuildArgs {
   mode: "reply" | "replyAll" | "forward";
   email: {
@@ -24,10 +35,24 @@ interface BuildArgs {
   locale: string;
   timeFormat: "12h" | "24h";
   unknownLabel: string;
+  /**
+   * Localized labels. Optional for backward compatibility; falls back to
+   * English (matching the original hardcoded behaviour) when not supplied.
+   */
+  labels?: QuoteHeaderLabels;
 }
 
+const DEFAULT_LABELS: QuoteHeaderLabels = {
+  formatReplyLine: ({ date, from }) => `On ${date}, ${from} wrote:`,
+  forwardedSeparator: "---------- Forwarded message ----------",
+  fromLabel: "From",
+  dateLabel: "Date",
+  subjectLabel: "Subject",
+};
+
 function defaultHeader(args: BuildArgs): QuoteHeader {
   const { mode, email, timeFormat, unknownLabel } = args;
+  const labels = args.labels ?? DEFAULT_LABELS;
   const date = email.receivedAt
     ? formatDateTime(email.receivedAt, timeFormat, {
         weekday: "short",
@@ -38,16 +63,25 @@ function defaultHeader(args: BuildArgs): QuoteHeader {
     : "";
   const from = email.from?.[0];
   const fromStr = from ? `${from.name || from.email}` : unknownLabel;
+  // Forward header "From:" shows the full sender incl. address ("Name
+  // <email>"), like every mail client. The reply line keeps the bare name
+  // (reads more naturally in "On … wrote:").
+  const fromStrFull = from
+    ? (from.name && from.email && from.name !== from.email
+        ? `${from.name} <${from.email}>`
+        : (from.email || from.name || unknownLabel))
+    : unknownLabel;
   const subject = email.subject || "";
 
   if (mode === "forward") {
-    const text = `---------- Forwarded message ----------\nFrom: ${fromStr}\nDate: ${date}\nSubject: ${subject}\n`;
-    const html = `<div>---------- Forwarded message ----------<br>From: ${fromStr}<br>Date: ${date}<br>Subject: ${subject}<br><br></div>`;
+    const text = `${labels.forwardedSeparator}\n${labels.fromLabel}: ${fromStrFull}\n${labels.dateLabel}: ${date}\n${labels.subjectLabel}: ${subject}\n`;
+    const html = `<div>${labels.forwardedSeparator}<br>${labels.fromLabel}: ${fromStrFull}<br>${labels.dateLabel}: ${date}<br>${labels.subjectLabel}: ${subject}<br><br></div>`;
     return { html, text, wrapInBlockquote: false };
   }
 
-  const text = `On ${date}, ${fromStr} wrote:\n`;
-  const html = `<div>On ${date}, ${fromStr} wrote:<br></div>`;
+  const replyLine = labels.formatReplyLine({ date, from: fromStr });
+  const text = `${replyLine}\n`;
+  const html = `<div>${replyLine}<br></div>`;
   return { html, text, wrapInBlockquote: true };
 }