feat: project EmailReadView for email-banner slot, expose auth results

lib/plugin-projection.ts

@@ -0,0 +1,25 @@
+// Projection helpers — convert host-internal types into the read-only views
+// that plugins consume. Keeping this in one place ensures every slot/hook
+// hands plugins the same shape declared in plugin-types.ts.
+
+import type { Email } from '@/lib/jmap/types';
+import type { EmailReadView } from '@/lib/plugin-types';
+
+export function emailToReadView(email: Email): EmailReadView {
+  return {
+    id: email.id,
+    threadId: email.threadId,
+    mailboxIds: Object.keys(email.mailboxIds || {}).filter(k => email.mailboxIds[k]),
+    from: (email.from || []).map(a => ({ name: a.name || '', email: a.email })),
+    to: (email.to || []).map(a => ({ name: a.name || '', email: a.email })),
+    cc: (email.cc || []).map(a => ({ name: a.name || '', email: a.email })),
+    subject: email.subject || '',
+    receivedAt: email.receivedAt,
+    isRead: !!email.keywords?.['$seen'],
+    isFlagged: !!email.keywords?.['$flagged'],
+    hasAttachment: email.hasAttachment,
+    preview: email.preview || '',
+    keywords: Object.keys(email.keywords || {}).filter(k => email.keywords[k]),
+    auth: email.authenticationResults,
+  };
+}