added IMAP, LetsEncrypt, update layout

internal/mailstore/quota.go

@@ -0,0 +1,19 @@
+package mailstore
+
+import "fmt"
+
+// QuotaStatus reports a mailbox's storage usage — feeds the "≥90% full" badge on the
+// mailboxes list and the dashboard tile in a later milestone.
+func (s *Store) QuotaStatus(mailboxID int64) (used, quota int64, pctFull float64, err error) {
+	mbox, err := s.DB.GetMailboxByID(mailboxID)
+	if err != nil {
+		return 0, 0, 0, err
+	}
+	if mbox == nil {
+		return 0, 0, 0, fmt.Errorf("mailstore: mailbox %d not found", mailboxID)
+	}
+	if mbox.QuotaBytes == 0 {
+		return mbox.UsedBytes, 0, 0, nil
+	}
+	return mbox.UsedBytes, mbox.QuotaBytes, float64(mbox.UsedBytes) / float64(mbox.QuotaBytes) * 100, nil
+}