feat(billing-v2-c): UI префлайт Task 1.10 — баннер заморозки, индикатор ёмкости, диалог перегрузки

Spec C §3.6/§6.2. Бэкенд: GET /api/billing/balance-status (frozen + capacity + required + дефицит ₽/leads), Pest 6. Фронт: BalanceFrozenBanner (в AppLayout, глобально), BalanceCapacityIndicator (в BillingView под балансом), ProjectLimitOverloadDialog (409-перехват в NewProjectDialog: save-blocked/set-zero), tenantStore + api getBalanceStatus. Vitest +18.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/app/Http/Controllers/Api/BillingController.php

@@ -6,11 +6,14 @@ namespace App\Http\Controllers\Api;
 
 use App\Http\Controllers\Controller;
 use App\Models\BalanceTransaction;
+use App\Models\PricingTier;
+use App\Models\Project;
 use App\Models\Tenant;
 use App\Models\User;
 use App\Repositories\PricingTierRepository;
 use App\Services\Billing\BalanceToLeadsConverter;
 use App\Services\Billing\BillingTopupService;
+use Illuminate\Database\Eloquent\Collection;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;
 use Illuminate\Support\Carbon;
@@ -111,6 +114,101 @@ class BillingController extends Controller
         ]);
     }
 
+    /**
+     * GET /api/billing/balance-status — лёгкий статус баланса для UI префлайта
+     * (Billing v2 Spec C §3.6). Питает глобальный баннер заморозки
+     * (BalanceFrozenBanner: frozen_by_balance_at + дефицит) и индикатор ёмкости
+     * (BalanceCapacityIndicator: balance / capacity / required). Грузится в
+     * AppLayout на всех страницах, поэтому без tiers_preview и истории.
+     */
+    public function balanceStatus(Request $request): JsonResponse
+    {
+        /** @var User $user */
+        $user = $request->user();
+        /** @var Tenant $tenant */
+        $tenant = Tenant::query()->findOrFail((int) $user->tenant_id);
+
+        $activeTiers = app(PricingTierRepository::class)->activeAt(Carbon::now('Europe/Moscow'));
+        $deliveredInMonth = (int) ($tenant->delivered_in_month ?? 0);
+
+        $capacityLeads = (int) app(BalanceToLeadsConverter::class)->convert(
+            (string) $tenant->balance_rub,
+            $deliveredInMonth,
+            $activeTiers,
+        )['leads'];
+
+        // Требуемые лиды/день — сумма лимитов активных не-заблокированных проектов
+        // (та же выборка, что в ProjectController preflight).
+        $requiredLeads = (int) Project::query()
+            ->where('tenant_id', $tenant->id)
+            ->where('is_active', true)
+            ->whereNull('preflight_blocked_at')
+            ->sum('daily_limit_target');
+
+        $deficitLeads = max(0, $requiredLeads - $capacityLeads);
+        $deficitRub = '0.00';
+        if ($deficitLeads > 0) {
+            $needed = $this->minBalanceForLeads($requiredLeads, $deliveredInMonth, $activeTiers);
+            $deficitRub = bcsub($needed, (string) $tenant->balance_rub, 2);
+            if (bccomp($deficitRub, '0', 2) < 0) {
+                $deficitRub = '0.00';
+            }
+        }
+
+        return response()->json([
+            'frozen_by_balance_at' => $tenant->frozen_by_balance_at?->toISOString(),
+            'balance_rub' => (string) $tenant->balance_rub,
+            'capacity_leads' => $capacityLeads,
+            'required_leads_per_day' => $requiredLeads,
+            'deficit_leads' => $deficitLeads,
+            'deficit_rub' => $deficitRub,
+        ]);
+    }
+
+    /**
+     * Минимальный баланс (₽, scale 2), чтобы позволить себе $leads лидов при уже
+     * доставленных $deliveredInMonth в этом месяце — сумма цен ступеней по позициям
+     * [delivered .. delivered+leads-1]. Зеркалит логику BalanceToLeadsConverter.
+     *
+     * @param  Collection<int, PricingTier>  $tiers
+     */
+    private function minBalanceForLeads(int $leads, int $deliveredInMonth, $tiers): string
+    {
+        if ($leads <= 0) {
+            return '0.00';
+        }
+
+        $sorted = $tiers
+            ->filter(fn ($t) => (bool) $t->is_active)
+            ->sortBy('tier_no')
+            ->values();
+
+        $kopecks = '0';
+        $remaining = $leads;
+        $cumulative = 0;            // позиции [0..cumulative) пройдены предыдущими ступенями
+        $position = $deliveredInMonth;
+
+        foreach ($sorted as $tier) {
+            $unlimited = $tier->leads_in_tier === null;
+            $tierEnd = $unlimited ? PHP_INT_MAX : $cumulative + (int) $tier->leads_in_tier;
+
+            $slotsInTier = max(0, $tierEnd - max($cumulative, $position));
+            if ($slotsInTier > 0) {
+                $take = min($remaining, $slotsInTier);
+                $kopecks = bcadd($kopecks, bcmul((string) (int) $tier->price_per_lead_kopecks, (string) $take, 0), 0);
+                $remaining -= $take;
+                $position += $take;
+            }
+
+            if ($remaining <= 0 || $unlimited) {
+                break;
+            }
+            $cumulative = $tierEnd;
+        }
+
+        return bcdiv($kopecks, '100', 2);
+    }
+
     /**
      * GET /api/billing/transactions?type=topup|lead_charge|migration&page=N
      * — пагинированная история balance_transactions тенанта (20/страница).