Fix 500 when exiting hosting panel for existing accounts.

The account overview queried a local mailboxes table that the extracted hosting app does not have; guard those lookups and skip email-addon upsells when mailboxes are managed on Ladill Email.

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

app/Services/Hosting/HostingMailboxService.php

@@ -26,11 +26,12 @@ class HostingMailboxService
      */
     public function usageSummary(HostingAccount $account): array
     {
-        $account->loadMissing(['product', 'mailboxes']);
+        $account->loadMissing(['product']);
 
+        $mailboxes = $account->loadedMailboxes();
         $freeAllowance = $account->freeEmailAllowance();
-        $mailboxCount = $account->mailboxes->count();
-        $paidCount = $account->mailboxes->where('is_paid', true)->count();
+        $mailboxCount = $mailboxes->count();
+        $paidCount = $mailboxes->where('is_paid', true)->count();
         $freeUsed = $freeAllowance === null ? $mailboxCount : min($mailboxCount, $freeAllowance);
         $extraCount = max($mailboxCount - ($freeAllowance ?? $mailboxCount), 0);
 
@@ -53,7 +54,15 @@ class HostingMailboxService
 
     public function createMailbox(HostingAccount $account, array $input): array
     {
-        $account->loadMissing(['product', 'mailboxes', 'sites']);
+        $account->loadMissing(['product', 'sites']);
+
+        if (! HostingAccount::tracksLocalMailboxes()) {
+            throw ValidationException::withMessages([
+                'local_part' => 'Mailbox creation is managed in Ladill Email.',
+            ]);
+        }
+
+        $account->loadMissing(['mailboxes']);
 
         $domain = Domain::query()
             ->whereKey((int) ($input['domain_id'] ?? 0))
@@ -113,11 +122,11 @@ class HostingMailboxService
 
         ProvisionMailboxJob::dispatch($mailbox->id, encrypt((string) $input['password']));
 
-        $invoice = $this->syncAddonInvoice($account->fresh(['mailboxes']));
+        $invoice = $this->syncAddonInvoice($account->fresh());
 
         return [
             'mailbox' => $mailbox->fresh(['domain']),
-            'usage' => $this->usageSummary($account->fresh(['product', 'mailboxes'])),
+            'usage' => $this->usageSummary($account->fresh(['product'])),
             'invoice' => $invoice,
         ];
     }
@@ -133,12 +142,12 @@ class HostingMailboxService
         $mailbox->update(['status' => 'deleting']);
         DeactivateMailboxJob::dispatch($mailbox->id);
 
-        return $this->syncAddonInvoice($account->fresh(['mailboxes']));
+        return $this->syncAddonInvoice($account->fresh());
     }
 
     public function syncAddonInvoice(HostingAccount $account): ?HostingBillingInvoice
     {
-        $account->loadMissing(['product', 'mailboxes']);
+        $account->loadMissing(['product']);
         $summary = $this->usageSummary($account);
         if ($summary['extra_count'] === 0) {
             HostingBillingInvoice::query()