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>

tests/Feature/SuiviTest.php

@@ -236,6 +236,124 @@ it('returns no progress for a category without a budget defined', function (): v
     expect($component->viewData('categoryProgress')[$category->id])->toBeNull();
 });
 
+it('records who paid a transaction and defaults to common when none is selected', function (): void {
+    $user = User::factory()->create();
+    $household = $user->currentHousehold;
+    $category = $household->categories()->create(['name' => 'Loyer', 'type' => 'depense', 'position' => 1]);
+
+    Livewire::actingAs($user)
+        ->test(Index::class)
+        ->set('categoryId', $category->id)
+        ->set('amount', '1200')
+        ->call('addTransaction');
+
+    $transaction = $household->transactions()->first();
+
+    expect($transaction->paid_by_user_id)->toBeNull();
+});
+
+it('assigns a transaction to a household member when selected', function (): void {
+    $owner = User::factory()->create();
+    $member = User::factory()->create();
+    $household = $owner->currentHousehold;
+    $member->households()->attach($household->id, ['role' => 'member']);
+
+    $category = $household->categories()->create(['name' => 'Loyer', 'type' => 'depense', 'position' => 1]);
+
+    Livewire::actingAs($owner)
+        ->test(Index::class)
+        ->set('categoryId', $category->id)
+        ->set('amount', '1200')
+        ->set('paidByUserId', (string) $member->id)
+        ->call('addTransaction');
+
+    $transaction = $household->transactions()->first();
+
+    expect($transaction->paid_by_user_id)->toBe($member->id);
+});
+
+it('ignores a paid-by user id that does not belong to the household', function (): void {
+    $owner = User::factory()->create();
+    $outsider = User::factory()->create();
+    $household = $owner->currentHousehold;
+    $category = $household->categories()->create(['name' => 'Loyer', 'type' => 'depense', 'position' => 1]);
+
+    Livewire::actingAs($owner)
+        ->test(Index::class)
+        ->set('categoryId', $category->id)
+        ->set('amount', '1200')
+        ->set('paidByUserId', (string) $outsider->id)
+        ->call('addTransaction');
+
+    $transaction = $household->transactions()->first();
+
+    expect($transaction->paid_by_user_id)->toBeNull();
+});
+
+it('filters transactions by who paid without affecting the running balance', function (): void {
+    $owner = User::factory()->create();
+    $member = User::factory()->create();
+    $household = $owner->currentHousehold;
+    $member->households()->attach($household->id, ['role' => 'member']);
+
+    $revenu = $household->categories()->create(['name' => 'Salaire', 'type' => 'revenu', 'position' => 1]);
+    $depense = $household->categories()->create(['name' => 'Loyer', 'type' => 'depense', 'position' => 1]);
+
+    $household->transactions()->create([
+        'category_id' => $revenu->id, 'user_id' => $owner->id,
+        'date' => '2026-01-01', 'date_effective' => '2026-01-01', 'amount' => 2000,
+    ]);
+    $ownerTx = $household->transactions()->create([
+        'category_id' => $depense->id, 'user_id' => $owner->id, 'paid_by_user_id' => $owner->id,
+        'date' => '2026-01-02', 'date_effective' => '2026-01-02', 'amount' => 500,
+    ]);
+    $memberTx = $household->transactions()->create([
+        'category_id' => $depense->id, 'user_id' => $owner->id, 'paid_by_user_id' => $member->id,
+        'date' => '2026-01-03', 'date_effective' => '2026-01-03', 'amount' => 300,
+    ]);
+
+    $component = Livewire::actingAs($owner)->test(Index::class)->set('filterPaidBy', (string) $member->id);
+
+    $shown = $component->viewData('transactions');
+    expect($shown->pluck('id'))->toContain($memberTx->id);
+    expect($shown->pluck('id'))->not->toContain($ownerTx->id);
+
+    // Le solde reste calculé sur toutes les transactions malgré le filtre d'affichage.
+    $running = $component->viewData('running');
+    expect($running[$memberTx->id])->toBe(1200.0); // 2000 - 500 - 300
+});
+
+it('summarizes this month depenses by payer including common', function (): void {
+    $this->travelTo(now()->setDate(2026, 3, 10));
+
+    $owner = User::factory()->create();
+    $member = User::factory()->create();
+    $household = $owner->currentHousehold;
+    $member->households()->attach($household->id, ['role' => 'member']);
+
+    $category = $household->categories()->create(['name' => 'Loyer', 'type' => 'depense', 'position' => 1]);
+
+    $household->transactions()->create([
+        'category_id' => $category->id, 'user_id' => $owner->id, 'paid_by_user_id' => $owner->id,
+        'date' => '2026-03-05', 'date_effective' => '2026-03-05', 'amount' => 500,
+    ]);
+    $household->transactions()->create([
+        'category_id' => $category->id, 'user_id' => $owner->id, 'paid_by_user_id' => $member->id,
+        'date' => '2026-03-06', 'date_effective' => '2026-03-06', 'amount' => 300,
+    ]);
+    $household->transactions()->create([
+        'category_id' => $category->id, 'user_id' => $owner->id, 'paid_by_user_id' => null,
+        'date' => '2026-03-07', 'date_effective' => '2026-03-07', 'amount' => 100,
+    ]);
+
+    $component = Livewire::actingAs($owner)->test(Index::class);
+    $summary = $component->viewData('paidBySummary')->keyBy('label');
+
+    expect($summary[$owner->name]['total'])->toBe(500.0);
+    expect($summary[$member->name]['total'])->toBe(300.0);
+    expect($summary['Commun']['total'])->toBe(100.0);
+});
+
 it('does not show another household transactions', function (): void {
     $ownerA = User::factory()->create();
     $ownerB = User::factory()->create();