#3: close 3 known F1 gaps - folder/mailbox counters, quota-at-RCPT, alias fan-out

Per feature/3-f0-f1-validation's own gap analysis (commit 097fa37):

- InboundMessageRepository.Persist now updates folders.unread_count,
  folders.total_count, and mailboxes.used_bytes in the same transaction
  as the message insert (PLAN.md section 6.1 "++counters" was a no-op
  before this).
- MailboxRecord carries QuotaBytes/UsedBytes; ResolveRecipient rejects
  RCPT with 452 4.2.2 when a target mailbox has already reached its
  quota (used_bytes >= quota_bytes), before DATA - never silently
  accepting mail into a full mailbox.
- MailboxRepository.ResolveDeliveryTargets tries a direct mailbox match
  first, then falls back to the aliases table (exact source_address
  match takes precedence over a domain catch-all). One RCPT TO can now
  fan out to multiple mailboxes; alias destinations that don't resolve
  to an internal active mailbox are silently skipped, since outbound/
  external forwarding doesn't exist yet. postmaster@/abuse@/dmarc@-style
  aliases now actually deliver.

The E2E test's counters_updated subtest flips from a documented KNOWN
GAP (t.Skipf) to a hard assertion now that it passes, and gains two new
subtests (quota_rejected_when_mailbox_full, alias_resolves_to_destination_mailbox)
covering the other two fixes end-to-end. New unit and Postgres
integration test coverage added for all three fixes at every layer.

Verified: full suite green on Windows (unit + E2E via embedded
Postgres, no Docker needed) and via WSL Docker against the real
docker-compose Postgres (all infrastructure/postgres and diskstorage
integration tests, not just E2E). lang-lint clean.

services/protocols/internal/infrastructure/postgres/inbound_message_repository.go

@@ -39,8 +39,11 @@ func (r *InboundMessageRepository) Persist(ctx context.Context, input port.Persi
 		return 0, fmt.Errorf("find inbox folder for mailbox %s: %w", input.MailboxID, err)
 	}
 
-	if _, err := tx.Exec(ctx, `UPDATE folders SET uid_next = uid_next + 1 WHERE id = $1`, folderID); err != nil {
-		return 0, fmt.Errorf("advance uid_next: %w", err)
+	if _, err := tx.Exec(ctx, `
+		UPDATE folders SET uid_next = uid_next + 1, unread_count = unread_count + 1, total_count = total_count + 1
+		WHERE id = $1
+	`, folderID); err != nil {
+		return 0, fmt.Errorf("advance uid_next and folder counters: %w", err)
 	}
 
 	// email_messages.id defaults to gen_random_uuid() per the migration - no explicit value needed.
@@ -61,6 +64,10 @@ func (r *InboundMessageRepository) Persist(ctx context.Context, input port.Persi
 		return 0, fmt.Errorf("increment blob ref_count: %w", err)
 	}
 
+	if _, err := tx.Exec(ctx, `UPDATE mailboxes SET used_bytes = used_bytes + $1 WHERE id = $2`, input.Blob.SizeBytes, input.MailboxID); err != nil {
+		return 0, fmt.Errorf("increment mailbox used_bytes: %w", err)
+	}
+
 	if _, err := tx.Exec(ctx, `
 		INSERT INTO domain_events_outbox (event_type, aggregate_id, payload)
 		VALUES ('EmailReceived', $1, $2)