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>

resources/views/livewire/recurring/index.blade.php

@@ -11,7 +11,7 @@
             @forelse ($recurrences as $recurring)
                 <li class="px-4 py-3">
                     @if ($editingId === $recurring->id)
-                        <form wire:submit="saveEdit" class="grid grid-cols-1 sm:grid-cols-4 gap-2 items-end">
+                        <form wire:submit="saveEdit" class="grid grid-cols-1 sm:grid-cols-5 gap-2 items-end">
                             <div>
                                 <label for="editing-name-{{ $recurring->id }}" class="sr-only">Nom</label>
                                 <input wire:model="editingName" id="editing-name-{{ $recurring->id }}" type="text" class="w-full bg-surface border-border-strong text-text rounded-md text-sm py-1" autofocus />
@@ -24,6 +24,15 @@
                                 <label for="editing-day-{{ $recurring->id }}" class="sr-only">Jour du mois</label>
                                 <input wire:model="editingDayOfMonth" id="editing-day-{{ $recurring->id }}" type="number" min="1" max="28" class="w-full bg-surface border-border-strong text-text rounded-md text-sm py-1" />
                             </div>
+                            <div>
+                                <label for="editing-paid-by-{{ $recurring->id }}" class="sr-only">Payé par</label>
+                                <select wire:model="editingPaidByUserId" id="editing-paid-by-{{ $recurring->id }}" class="w-full rounded-md bg-surface border-border-strong text-text text-sm py-1 focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring">
+                                    <option value="">Commun</option>
+                                    @foreach ($members as $member)
+                                        <option value="{{ $member->id }}">{{ $member->name }}</option>
+                                    @endforeach
+                                </select>
+                            </div>
                             <div class="flex items-center gap-3">
                                 <button type="submit" class="text-xs text-positive hover:underline rounded focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring">Sauver</button>
                                 <button type="button" wire:click="cancelEdit" class="text-xs text-text-muted hover:underline rounded focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring">Annuler</button>
@@ -37,7 +46,7 @@
                                     <span class="text-text-muted">— {{ $recurring->category->name }}</span>
                                 </p>
                                 <p class="text-xs text-text-muted">
-                                    {{ number_format($recurring->amount, 2, ',', ' ') }} € · le {{ $recurring->day_of_month }} de chaque mois
+                                    {{ number_format($recurring->amount, 2, ',', ' ') }} € · le {{ $recurring->day_of_month }} de chaque mois · {{ $recurring->paidBy?->name ?? 'Commun' }}
                                     @unless ($recurring->active) · <span class="text-danger">en pause</span> @endunless
                                 </p>
                             </div>
@@ -56,7 +65,7 @@
             @endforelse
         </ul>
 
-        <form wire:submit="add" class="px-4 py-4 bg-surface-alt grid grid-cols-1 sm:grid-cols-5 gap-3 items-end">
+        <form wire:submit="add" class="px-4 py-4 bg-surface-alt grid grid-cols-1 sm:grid-cols-6 gap-3 items-end">
             <div>
                 <x-input-label for="name" value="Nom" />
                 <x-text-input wire:model="name" id="name" type="text" class="block mt-1 w-full text-sm" placeholder="Loyer" />
@@ -82,6 +91,15 @@
                 <x-text-input wire:model="dayOfMonth" id="dayOfMonth" type="number" min="1" max="28" class="block mt-1 w-full text-sm" />
                 <x-input-error :messages="$errors->get('dayOfMonth')" class="mt-1" />
             </div>
+            <div>
+                <x-input-label for="paidByUserId" value="Payé par" />
+                <select wire:model="paidByUserId" id="paidByUserId" class="block mt-1 w-full rounded-md bg-surface border-border-strong text-text text-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring">
+                    <option value="">Commun</option>
+                    @foreach ($members as $member)
+                        <option value="{{ $member->id }}">{{ $member->name }}</option>
+                    @endforeach
+                </select>
+            </div>
             <div>
                 <x-primary-button class="w-full justify-center">Ajouter</x-primary-button>
             </div>