Track who paid each depense, with a "Commun" (shared) fallback

Adds a "payé par" field to transactions and recurring transactions:
either a household member or null (shared/common expense). No per-
member account balances — this is purely a "who paid" label, the
household's overall balance is unchanged and unaffected by any
filtering.

- paid_by_user_id nullable FK on transactions and recurring_transactions
- Suivi: "payé par" selector on both entry forms (desktop dropdown,
  mobile buttons), a filter above the transaction table, a "payé par"
  column, and a summary tile showing this month's depenses grouped
  by payer (including Commun)
- Recurring transactions carry paid_by_user_id onto the transaction
  they generate when confirmed
- Running balance is computed from all transactions regardless of
  the payer filter, so it never gets skewed by the active filter

11 new Pest tests (assignment, common fallback, non-member rejection,
filter isolation from the balance calc, per-payer summary, recurring
propagation). 69/69 total pass, Pint clean, verified end-to-end on
production data (desktop + mobile, test row created and removed).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/Livewire/Recurring/Index.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Livewire\Recurring;
 
+use App\Models\Household;
 use App\Models\RecurringTransaction;
 use Livewire\Attributes\Layout;
 use Livewire\Component;
@@ -19,6 +20,8 @@ class Index extends Component
 
     public string $dayOfMonth = '1';
 
+    public string $paidByUserId = '';
+
     public ?int $editingId = null;
 
     public string $editingName = '';
@@ -27,6 +30,23 @@ class Index extends Component
 
     public string $editingDayOfMonth = '1';
 
+    public string $editingPaidByUserId = '';
+
+    /**
+     * Vide ou "0" = dépense commune (aucun membre précis). Vérifie que la
+     * valeur, si fournie, correspond bien à un membre du foyer courant.
+     */
+    private function resolvePaidByUserId(Household $household, string $value): ?int
+    {
+        if ($value === '' || $value === '0') {
+            return null;
+        }
+
+        $isMember = $household->members()->whereKey((int) $value)->exists();
+
+        return $isMember ? (int) $value : null;
+    }
+
     public function add(): void
     {
         $this->validate([
@@ -34,6 +54,7 @@ class Index extends Component
             'categoryId' => ['required', 'exists:categories,id'],
             'amount' => ['required', 'numeric', 'min:0.01'],
             'dayOfMonth' => ['required', 'integer', 'min:1', 'max:28'],
+            'paidByUserId' => ['nullable', 'integer'],
         ]);
 
         $household = auth()->user()->currentHousehold;
@@ -41,12 +62,13 @@ class Index extends Component
 
         $household->recurringTransactions()->create([
             'category_id' => $category->id,
+            'paid_by_user_id' => $this->resolvePaidByUserId($household, $this->paidByUserId),
             'name' => $this->name,
             'amount' => $this->amount,
             'day_of_month' => $this->dayOfMonth,
         ]);
 
-        $this->reset(['name', 'categoryId', 'amount', 'dayOfMonth']);
+        $this->reset(['name', 'categoryId', 'amount', 'dayOfMonth', 'paidByUserId']);
         $this->dayOfMonth = '1';
     }
 
@@ -59,6 +81,7 @@ class Index extends Component
         $this->editingName = $recurring->name;
         $this->editingAmount = (string) $recurring->amount;
         $this->editingDayOfMonth = (string) $recurring->day_of_month;
+        $this->editingPaidByUserId = $recurring->paid_by_user_id ? (string) $recurring->paid_by_user_id : '';
     }
 
     public function saveEdit(): void
@@ -70,12 +93,16 @@ class Index extends Component
             'editingName' => ['required', 'string', 'max:255'],
             'editingAmount' => ['required', 'numeric', 'min:0.01'],
             'editingDayOfMonth' => ['required', 'integer', 'min:1', 'max:28'],
+            'editingPaidByUserId' => ['nullable', 'integer'],
         ]);
 
+        $household = auth()->user()->currentHousehold;
+
         $recurring->update([
             'name' => $this->editingName,
             'amount' => $this->editingAmount,
             'day_of_month' => $this->editingDayOfMonth,
+            'paid_by_user_id' => $this->resolvePaidByUserId($household, $this->editingPaidByUserId),
         ]);
 
         $this->editingId = null;
@@ -107,7 +134,7 @@ class Index extends Component
         $household = auth()->user()->currentHousehold;
 
         $recurrences = $household->recurringTransactions()
-            ->with('category')
+            ->with(['category', 'paidBy'])
             ->orderBy('day_of_month')
             ->get();
 
@@ -117,9 +144,12 @@ class Index extends Component
             ->orderBy('position')
             ->get();
 
+        $members = $household->members()->orderBy('name')->get();
+
         return view('livewire.recurring.index', [
             'recurrences' => $recurrences,
             'categories' => $categories,
+            'members' => $members,
         ]);
     }
 }