FRE-696 Wire up API client to mail/contact/attachment endpoints

- Create ProtonMail API client (src/lib/mail/protonmail-client.ts)
- Add tRPC mail router with 8 endpoints (server/trpc/mail-router.ts)
- Wire mail router into appRouter (server/trpc/index.ts)
- Add module exports (src/lib/mail/index.ts)

Endpoints:
- mail.messages, mail.message, mail.send
- mail.contact, mail.contacts, mail.addContact
- mail.attachment, mail.attachmentDownload

Router uses Zod validation and includes placeholders for ProtonMail API calls.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/lib/mail/index.ts

@@ -0,0 +1,2 @@
+export { ProtonMailClient, protonMail } from './protonmail-client';
+export type { ProtonMailMessage, ProtonMailAttachment, ProtonMailContact } from './protonmail-client';

src/lib/mail/protonmail-client.ts

@@ -0,0 +1,84 @@
+import { trpc } from '../api/trpc-client';
+
+export interface ProtonMailMessage {
+  id: string;
+  subject: string;
+  sender: { email: string; name?: string };
+  recipients: Array<{ email: string; name?: string }>;
+  body: string;
+  attachments?: ProtonMailAttachment[];
+  timestamp: string;
+  read: boolean;
+}
+
+export interface ProtonMailAttachment {
+  id: string;
+  filename: string;
+  mimeType: string;
+  size: number;
+  downloadUrl: string;
+}
+
+export interface ProtonMailContact {
+  id: string;
+  email: string;
+  name: string;
+  phone?: string;
+  organization?: string;
+}
+
+export class ProtonMailClient {
+  constructor(private baseUrl: string = `${(import.meta as any).env?.VITE_API_URL || 'http://localhost:8080'}`) {}
+
+  async getMessages(folder?: string): Promise<ProtonMailMessage[]> {
+    const result = await trpc.mail.messages.query({ folder });
+    return result;
+  }
+
+  async getMessage(messageId: string): Promise<ProtonMailMessage> {
+    const result = await trpc.mail.message.query({ messageId });
+    return result;
+  }
+
+  async sendMessage(
+    to: string[],
+    subject: string,
+    body: string,
+    attachments?: ProtonMailAttachment[]
+  ): Promise<ProtonMailMessage> {
+    const result = await trpc.mail.send.mutate({
+      to,
+      subject,
+      body,
+      attachments,
+    });
+    return result;
+  }
+
+  async getContact(email: string): Promise<ProtonMailContact | null> {
+    const result = await trpc.mail.contact.query({ email });
+    return result;
+  }
+
+  async getContacts(): Promise<ProtonMailContact[]> {
+    const result = await trpc.mail.contacts.query({});
+    return result;
+  }
+
+  async addContact(contact: Omit<ProtonMailContact, 'id'>): Promise<ProtonMailContact> {
+    const result = await trpc.mail.addContact.mutate(contact);
+    return result;
+  }
+
+  async getAttachment(attachmentId: string): Promise<ProtonMailAttachment> {
+    const result = await trpc.mail.attachment.query({ attachmentId });
+    return result;
+  }
+
+  async downloadAttachment(attachmentId: string): Promise<Blob> {
+    const result = await trpc.mail.attachmentDownload.query({ attachmentId });
+    return result;
+  }
+}
+
+export const protonMail = new ProtonMailClient();