refactor: extract ForwardEmail adapter to src/lib/forwardemail.ts

Mirrors the same pattern as cloudflare-email.ts — each provider has its
own adapter that translates provider-specific input into ProcessEmailInput
and delegates to processEmail(). inbound.ts is now a thin HTTP handler.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/forwardemail.ts

@@ -0,0 +1,62 @@
+import { EmailParser } from "../utils/email-parser";
+import { Env } from "../types";
+import { processEmail } from "./email-processor";
+
+export interface ForwardEmailPayload {
+  recipients?: string[];
+  from?: {
+    value?: Array<{ address?: string; name?: string }>;
+    text?: string;
+    html?: string;
+  };
+  subject?: string;
+  text?: string;
+  html?: string;
+  date?: string;
+  messageId?: string;
+  headerLines?: Array<{ key: string; line: string }>;
+  headers?: string;
+  raw?: string;
+  attachments?: Array<any>;
+}
+
+function normalizeEmail(value: string): string {
+  return value.trim().toLowerCase();
+}
+
+function extractSenderAddresses(payload: ForwardEmailPayload): string[] {
+  const valueEntries = payload.from?.value || [];
+  const structuredAddresses = valueEntries
+    .map((entry) => entry.address || "")
+    .map(normalizeEmail)
+    .filter(Boolean);
+
+  if (structuredAddresses.length > 0) {
+    return Array.from(new Set(structuredAddresses));
+  }
+
+  const fromText = payload.from?.text || "";
+  const matches =
+    fromText.match(/[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}/gi) || [];
+  return Array.from(new Set(matches.map(normalizeEmail)));
+}
+
+export async function handleForwardEmail(
+  payload: ForwardEmailPayload,
+  env: Env,
+): Promise<Response> {
+  const emailData = EmailParser.parseForwardEmailPayload(payload);
+
+  return processEmail(
+    {
+      toAddress: payload.recipients?.[0] || "",
+      from: emailData.from,
+      senders: extractSenderAddresses(payload),
+      subject: emailData.subject,
+      content: emailData.content,
+      receivedAt: emailData.receivedAt,
+      headers: emailData.headers,
+    },
+    env,
+  );
+}