feat: Establish initial application structure, theming, responsive utilities, and core feature screens.

lib/core/utils/responsive_layout.dart

@@ -0,0 +1,122 @@
+import 'package:flutter/material.dart';
+
+/// Responsive breakpoints and layout utilities
+class ResponsiveLayout {
+  ResponsiveLayout._();
+
+  // ============ BREAKPOINTS ============
+  static const double mobileBreakpoint = 600;
+  static const double tabletBreakpoint = 900;
+  static const double desktopBreakpoint = 1200;
+
+  /// Check if current screen is mobile size
+  static bool isMobile(BuildContext context) {
+    return MediaQuery.of(context).size.width < mobileBreakpoint;
+  }
+
+  /// Check if current screen is tablet size
+  static bool isTablet(BuildContext context) {
+    final width = MediaQuery.of(context).size.width;
+    return width >= mobileBreakpoint && width < desktopBreakpoint;
+  }
+
+  /// Check if current screen is desktop size
+  static bool isDesktop(BuildContext context) {
+    return MediaQuery.of(context).size.width >= desktopBreakpoint;
+  }
+
+  /// Get current device type
+  static DeviceType getDeviceType(BuildContext context) {
+    final width = MediaQuery.of(context).size.width;
+    if (width < mobileBreakpoint) return DeviceType.mobile;
+    if (width < desktopBreakpoint) return DeviceType.tablet;
+    return DeviceType.desktop;
+  }
+
+  /// Get responsive value based on screen size
+  static T value<T>(
+    BuildContext context, {
+    required T mobile,
+    T? tablet,
+    required T desktop,
+  }) {
+    final type = getDeviceType(context);
+    switch (type) {
+      case DeviceType.mobile:
+        return mobile;
+      case DeviceType.tablet:
+        return tablet ?? desktop;
+      case DeviceType.desktop:
+        return desktop;
+    }
+  }
+
+  /// Get grid columns based on screen size
+  static int gridColumns(BuildContext context) {
+    return value(context, mobile: 2, tablet: 3, desktop: 4);
+  }
+
+  /// Get content max width
+  static double maxContentWidth(BuildContext context) {
+    return value(context, mobile: double.infinity, tablet: 900, desktop: 1200);
+  }
+}
+
+/// Device types for responsive layouts
+enum DeviceType { mobile, tablet, desktop }
+
+/// Widget that adapts layout based on screen size
+class AdaptiveLayout extends StatelessWidget {
+  final Widget mobile;
+  final Widget? tablet;
+  final Widget desktop;
+
+  const AdaptiveLayout({
+    super.key,
+    required this.mobile,
+    this.tablet,
+    required this.desktop,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return LayoutBuilder(
+      builder: (context, constraints) {
+        if (constraints.maxWidth < ResponsiveLayout.mobileBreakpoint) {
+          return mobile;
+        }
+        if (constraints.maxWidth < ResponsiveLayout.desktopBreakpoint) {
+          return tablet ?? desktop;
+        }
+        return desktop;
+      },
+    );
+  }
+}
+
+/// Wrapper that constrains content width on large screens
+class ResponsiveContainer extends StatelessWidget {
+  final Widget child;
+  final EdgeInsetsGeometry padding;
+
+  const ResponsiveContainer({
+    super.key,
+    required this.child,
+    this.padding = const EdgeInsets.symmetric(horizontal: 16),
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: ConstrainedBox(
+        constraints: BoxConstraints(
+          maxWidth: ResponsiveLayout.maxContentWidth(context),
+        ),
+        child: Padding(
+          padding: padding,
+          child: child,
+        ),
+      ),
+    );
+  }
+}