fix(mobile): URL changement mdp corrigée + v3.0 — multi-org, AppAuth, sécurité prod

Auth:
- profile_repository.dart: /api/auth/change-password → /api/membres/auth/change-password

Multi-org (Phase 3):
- OrgSelectorPage, OrgSwitcherBloc, OrgSwitcherEntry
- org_context_service.dart: headers X-Active-Organisation-Id + X-Active-Role

Navigation:
- MorePage: navigation conditionnelle par typeOrganisation
- Suppression adaptive_navigation (remplacé par main_navigation_layout)

Auth AppAuth:
- keycloak_webview_auth_service: fixes AppAuth Android
- AuthBloc: gestion REAUTH_REQUIS + premierLoginComplet

Onboarding:
- Nouveaux états: payment_method_page, onboarding_shared_widgets
- SouscriptionStatusModel mis à jour StatutValidationSouscription

Android:
- build.gradle: ProGuard/R8, network_security_config
- Gradle wrapper mis à jour

lib/features/onboarding/presentation/pages/onboarding_shared_widgets.dart

@@ -0,0 +1,169 @@
+import 'package:flutter/material.dart';
+import '../../../../shared/design_system/tokens/unionflow_colors.dart';
+
+/// Header commun à toutes les étapes d'onboarding
+class OnboardingStepHeader extends StatelessWidget {
+  final int step;
+  final int total;
+  final String title;
+  final String subtitle;
+
+  const OnboardingStepHeader({
+    super.key,
+    required this.step,
+    required this.total,
+    required this.title,
+    required this.subtitle,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      decoration: const BoxDecoration(
+        gradient: UnionFlowColors.primaryGradient,
+      ),
+      child: SafeArea(
+        bottom: false,
+        child: Padding(
+          padding: const EdgeInsets.fromLTRB(20, 12, 20, 24),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Row(
+                children: List.generate(total, (i) {
+                  final done = i < step;
+                  return Expanded(
+                    child: Container(
+                      height: 4,
+                      margin: EdgeInsets.only(right: i < total - 1 ? 6 : 0),
+                      decoration: BoxDecoration(
+                        color: done
+                            ? Colors.white
+                            : Colors.white.withOpacity(0.3),
+                        borderRadius: BorderRadius.circular(2),
+                      ),
+                    ),
+                  );
+                }),
+              ),
+              const SizedBox(height: 6),
+              Text(
+                'Étape $step sur $total',
+                style: TextStyle(
+                  color: Colors.white.withOpacity(0.75),
+                  fontSize: 12,
+                  fontWeight: FontWeight.w500,
+                ),
+              ),
+              const SizedBox(height: 12),
+              Text(
+                title,
+                style: const TextStyle(
+                  color: Colors.white,
+                  fontSize: 22,
+                  fontWeight: FontWeight.w800,
+                ),
+              ),
+              const SizedBox(height: 4),
+              Text(
+                subtitle,
+                style: TextStyle(
+                  color: Colors.white.withOpacity(0.8),
+                  fontSize: 13,
+                  height: 1.4,
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+/// Titre de section avec icône
+class OnboardingSectionTitle extends StatelessWidget {
+  final IconData icon;
+  final String title;
+
+  const OnboardingSectionTitle({
+    super.key,
+    required this.icon,
+    required this.title,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      children: [
+        Icon(icon, color: UnionFlowColors.unionGreen, size: 20),
+        const SizedBox(width: 8),
+        Text(
+          title,
+          style: const TextStyle(
+            color: UnionFlowColors.textPrimary,
+            fontWeight: FontWeight.w700,
+            fontSize: 16,
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+/// Barre de bouton principale en bas de page
+class OnboardingBottomBar extends StatelessWidget {
+  final bool enabled;
+  final String label;
+  final VoidCallback onPressed;
+
+  const OnboardingBottomBar({
+    super.key,
+    required this.enabled,
+    required this.label,
+    required this.onPressed,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: EdgeInsets.fromLTRB(
+          20, 12, 20, MediaQuery.of(context).padding.bottom + 12),
+      decoration: BoxDecoration(
+        color: UnionFlowColors.surface,
+        boxShadow: [
+          BoxShadow(
+            color: Colors.black.withOpacity(0.08),
+            blurRadius: 12,
+            offset: const Offset(0, -4),
+          ),
+        ],
+      ),
+      child: SizedBox(
+        width: double.infinity,
+        child: ElevatedButton(
+          onPressed: enabled ? onPressed : null,
+          style: ElevatedButton.styleFrom(
+            backgroundColor: UnionFlowColors.unionGreen,
+            disabledBackgroundColor: UnionFlowColors.border,
+            foregroundColor: Colors.white,
+            padding: const EdgeInsets.symmetric(vertical: 15),
+            shape: RoundedRectangleBorder(
+              borderRadius: BorderRadius.circular(14),
+            ),
+            elevation: enabled ? 2 : 0,
+            shadowColor: UnionFlowColors.unionGreen.withOpacity(0.4),
+          ),
+          child: Text(
+            label,
+            style: const TextStyle(
+              fontSize: 16,
+              fontWeight: FontWeight.w700,
+              letterSpacing: 0.3,
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}