feat: Implement agent network management and refactor app navigation with a new AppShell component.

lib/core/widgets/app_bottom_nav_bar.dart

@@ -0,0 +1,122 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_svg/flutter_svg.dart';
+import 'package:go_router/go_router.dart';
+import 'package:real_estate_mobile/core/constants/app_colors.dart';
+import 'package:real_estate_mobile/features/auth/presentation/providers/auth_provider.dart';
+
+/// Determines which tab is active based on the current route.
+int _currentTabIndex(BuildContext context) {
+  final location = GoRouterState.of(context).matchedLocation;
+  if (location.startsWith('/messages')) return 2;
+  if (location.startsWith('/agents/search')) return 1;
+  if (location.startsWith('/profile')) return 3;
+  return 0; // home and everything else
+}
+
+class AppBottomNavBar extends ConsumerWidget {
+  const AppBottomNavBar({super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final selectedIndex = _currentTabIndex(context);
+
+    return Container(
+      decoration: const BoxDecoration(
+        color: Colors.white,
+        border: Border(
+          top: BorderSide(color: Color(0xFFE8E8E8), width: 1),
+        ),
+      ),
+      child: SafeArea(
+        top: false,
+        child: Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 12),
+          child: Row(
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
+            children: [
+              _NavItem(
+                svgPath: 'assets/icons/nav_home_icon.svg',
+                fallbackIcon: Icons.home,
+                isSelected: selectedIndex == 0,
+                onTap: () => context.go('/home'),
+              ),
+              _NavItem(
+                svgPath: 'assets/icons/nav_list_icon.svg',
+                fallbackIcon: Icons.list,
+                isSelected: selectedIndex == 1,
+                onTap: () => context.go('/agents/search'),
+              ),
+              _NavItem(
+                svgPath: 'assets/icons/nav_messages_icon.svg',
+                fallbackIcon: Icons.chat_bubble,
+                isSelected: selectedIndex == 2,
+                onTap: () {
+                  final authState = ref.read(authProvider);
+                  if (authState.status != AuthStatus.authenticated) {
+                    context.push('/login');
+                    return;
+                  }
+                  context.go('/messages');
+                },
+              ),
+              _NavItem(
+                svgPath: 'assets/icons/nav_profile_icon.svg',
+                fallbackIcon: Icons.person_outline,
+                isSelected: selectedIndex == 3,
+                onTap: () {
+                  final authState = ref.read(authProvider);
+                  if (authState.status != AuthStatus.authenticated) {
+                    context.push('/login');
+                    return;
+                  }
+                  context.go('/profile');
+                },
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class _NavItem extends StatelessWidget {
+  final String svgPath;
+  final IconData fallbackIcon;
+  final bool isSelected;
+  final VoidCallback onTap;
+
+  const _NavItem({
+    required this.svgPath,
+    required this.fallbackIcon,
+    required this.isSelected,
+    required this.onTap,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: onTap,
+      behavior: HitTestBehavior.opaque,
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+        child: SvgPicture.asset(
+          svgPath,
+          width: 24,
+          height: 24,
+          colorFilter: isSelected
+              ? const ColorFilter.mode(
+                  AppColors.primaryDark, BlendMode.srcIn)
+              : const ColorFilter.mode(
+                  AppColors.accentOrange, BlendMode.srcIn),
+          placeholderBuilder: (_) => Icon(
+            fallbackIcon,
+            size: 24,
+            color: isSelected ? AppColors.primaryDark : AppColors.accentOrange,
+          ),
+        ),
+      ),
+    );
+  }
+}

lib/core/widgets/app_shell.dart

@@ -0,0 +1,44 @@
+import 'package:flutter/material.dart';
+import 'package:real_estate_mobile/core/widgets/app_bottom_nav_bar.dart';
+import 'package:real_estate_mobile/features/home/presentation/widgets/home_header.dart';
+
+/// Root shell that provides the persistent header and bottom nav bar.
+/// Only the content area (child) swaps when navigating between tabs.
+class AppShell extends StatelessWidget {
+  final Widget child;
+
+  const AppShell({super.key, required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      backgroundColor: Colors.white,
+      body: Column(
+        children: [
+          SafeArea(
+            bottom: false,
+            child: const HomeHeader(),
+          ),
+          Expanded(
+            child: AnimatedSwitcher(
+              duration: const Duration(milliseconds: 200),
+              switchInCurve: Curves.easeOut,
+              switchOutCurve: Curves.easeIn,
+              transitionBuilder: (child, animation) {
+                return FadeTransition(
+                  opacity: animation,
+                  child: child,
+                );
+              },
+              child: KeyedSubtree(
+                key: ValueKey(child.runtimeType),
+                child: child,
+              ),
+            ),
+          ),
+        ],
+      ),
+      bottomNavigationBar: const AppBottomNavBar(),
+    );
+  }
+}