feat: consolidate backend and docker-compose setup

lib/features/auth/login_screen.dart

@@ -0,0 +1,147 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
+import '../../config/app_config.dart';
+import 'auth_provider.dart';
+
+class LoginScreen extends ConsumerStatefulWidget {
+  const LoginScreen({super.key});
+
+  @override
+  ConsumerState<LoginScreen> createState() => _LoginScreenState();
+}
+
+class _LoginScreenState extends ConsumerState<LoginScreen> {
+  final _idController = TextEditingController();
+  final _passwordController = TextEditingController();
+  final _formKey = GlobalKey<FormState>();
+  bool _isLoading = false;
+
+  void _handleLogin() async {
+    if (!_formKey.currentState!.validate()) return;
+
+    final id = _idController.text.trim();
+    final pwd = _passwordController.text.trim();
+
+    setState(() => _isLoading = true);
+
+    try {
+      await ref.read(authProvider.notifier).login(id, pwd);
+      if (mounted) {
+        context.go('/camera');
+      }
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(
+            content: Text(
+              e.toString().replaceAll(RegExp(r'DioException.*: '), ''),
+              style: const TextStyle(color: Colors.white),
+            ),
+            backgroundColor: AppConfig.errorColor,
+          ),
+        );
+      }
+    } finally {
+      if (mounted) {
+        setState(() => _isLoading = false);
+      }
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: SafeArea(
+        child: Center(
+          child: SingleChildScrollView(
+            padding: const EdgeInsets.all(32.0),
+            child: Form(
+              key: _formKey,
+              child: Column(
+                mainAxisAlignment: MainAxisAlignment.center,
+                crossAxisAlignment: CrossAxisAlignment.stretch,
+                children: [
+                  Image.asset(
+                    'assets/logo.png',
+                    width: 120,
+                    height: 120,
+                    errorBuilder: (context, error, stackTrace) => const Icon(
+                      Icons.storefront, 
+                      size: 80, 
+                      color: AppConfig.primaryColor
+                    ),
+                  ),
+                  const SizedBox(height: 24),
+                  Text(
+                    'Welcome Back',
+                    style: AppConfig.h1,
+                    textAlign: TextAlign.center,
+                  ),
+                  const SizedBox(height: 8),
+                  Text(
+                    'Sign in to sync your documents to the central server',
+                    style: AppConfig.bodyMedium,
+                    textAlign: TextAlign.center,
+                  ),
+                  const SizedBox(height: 48),
+                  TextFormField(
+                    controller: _idController,
+                    decoration: const InputDecoration(
+                      labelText: 'Admin Provided ID',
+                      prefixIcon: Icon(Icons.person_outline),
+                    ),
+                    validator: (value) {
+                      if (value == null || value.trim().isEmpty) {
+                        return 'Username/ID cannot be empty';
+                      }
+                      return null;
+                    },
+                  ),
+                  const SizedBox(height: 16),
+                  TextFormField(
+                    controller: _passwordController,
+                    obscureText: true,
+                    decoration: const InputDecoration(
+                      labelText: 'Password',
+                      prefixIcon: Icon(Icons.lock_outline),
+                    ),
+                    validator: (value) {
+                      if (value == null || value.trim().isEmpty) {
+                        return 'Password cannot be empty';
+                      }
+                      if (value.trim().length < 6) {
+                        return 'Password must be at least 6 characters';
+                      }
+                      return null;
+                    },
+                  ),
+                  const SizedBox(height: 32),
+                  SizedBox(
+                    height: 56,
+                    child: ElevatedButton(
+                      onPressed: _isLoading ? null : _handleLogin,
+                      child: _isLoading 
+                          ? const SizedBox(
+                              width: 24, 
+                              height: 24, 
+                              child: CircularProgressIndicator(color: Colors.white, strokeWidth: 3)
+                            ) 
+                          : const Text('Login'),
+                    ),
+                  ),
+                const SizedBox(height: 24),
+                Text(
+                  'Please contact the central admin for credentials.',
+                  style: AppConfig.bodySmall,
+                  textAlign: TextAlign.center,
+                ),
+              ],
+            ),
+          ),
+        ),
+        ),
+      ),
+    );
+  }
+}