feat(mails): add Workspace mail CLI with pagination and parsed from fields

Manage the OnlyOffice Mail addon via oo mails using existing ONLYOFFICE_* creds,
with automatic page fetching past the 25-message API cap and fromName/fromAddress columns.

Co-authored-by: Cursor <cursoragent@cursor.com>

mails_integration_test.go

@@ -0,0 +1,41 @@
+//go:build integration
+
+package onlyoffice
+
+import (
+	"context"
+	"testing"
+)
+
+func TestIntegrationMailList(t *testing.T) {
+	creds := GetEnvironmentCredentials()
+	if creds.Url == "" || creds.User == "" || creds.Password == "" {
+		t.Skip("ONLYOFFICE_URL/USER/PASS not set")
+	}
+	c := NewClient(creds)
+	ctx := context.Background()
+	if err := c.AuthenticateContext(ctx); err != nil {
+		t.Fatalf("auth: %v", err)
+	}
+	accounts, err := c.ListMailAccounts(ctx)
+	if err != nil {
+		t.Fatalf("ListMailAccounts: %v", err)
+	}
+	t.Logf("accounts=%d", len(accounts))
+
+	msgs, err := c.ListMailMessages(ctx, MailMessagesFilter{Folder: MailFolderInbox, Count: 3})
+	if err != nil {
+		t.Fatalf("ListMailMessages: %v", err)
+	}
+	if len(msgs) == 0 {
+		t.Skip("no inbox messages to inspect")
+	}
+	id := idFromMap(msgs[0], "id")
+	msg, err := c.GetMailMessage(ctx, id)
+	if err != nil {
+		t.Fatalf("GetMailMessage(%s): %v", id, err)
+	}
+	if msg["subject"] == nil {
+		t.Fatalf("message missing subject: %+v", msg)
+	}
+}