fix(ui): align right tile by reserving chevron space

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

frontend/lib/widgets/quotidien/couple_selector_bandeau.dart

@@ -147,6 +147,8 @@ class _CoupleCard extends StatelessWidget {
       child: Row(
         children: [
           Expanded(
+            child: Padding(
+              padding: const EdgeInsets.only(right: 12),
               child: _MembreTile(
                 photoUrl: couple.enfant.photoUrl,
                 name: (couple.enfant.prenom != null && couple.enfant.prenom!.isNotEmpty)
@@ -155,10 +157,10 @@ class _CoupleCard extends StatelessWidget {
                 fallbackIcon: Icons.child_care,
               ),
             ),
+          ),
           Container(
             width: 8,
             height: 44,
-            margin: const EdgeInsets.symmetric(horizontal: 12),
             decoration: const BoxDecoration(
               image: DecorationImage(
                 image: AssetImage(QuotidienTheme.pencilLineVerticalAsset),
@@ -167,6 +169,8 @@ class _CoupleCard extends StatelessWidget {
             ),
           ),
           Expanded(
+            child: Padding(
+              padding: const EdgeInsets.only(left: 12),
               child: _MembreTile(
                 photoUrl: couple.am.photoUrl,
                 name: (couple.am.prenom != null && couple.am.prenom!.isNotEmpty)
@@ -181,13 +185,15 @@ class _CoupleCard extends StatelessWidget {
                     : Icons.person_outline,
               ),
             ),
-          if (showChevron)
-            const Padding(
-              padding: EdgeInsets.only(left: 4),
-              child: Icon(
+          ),
+          SizedBox(
+            width: 28,
+            child: showChevron 
+              ? const Icon(
                   Icons.keyboard_arrow_down,
                   color: QuotidienTheme.ink,
-              ),
+                )
+              : null,
           ),
         ],
       ),