chore: bring flutter client, docs, deploy and tools into monorepo

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

musify_flutter/.agents/skills/flutter-expert/references/bloc-state.md

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+# Bloc State Management
+
+## When to Use Bloc
+
+Use **Bloc/Cubit** when you need:
+
+* Explicit event → state transitions
+* Complex business logic
+* Predictable, testable flows
+* Clear separation between UI and logic
+
+| Use Case               | Recommended |
+| ---------------------- | ----------- |
+| Simple mutable state   | Riverpod    |
+| Event-driven workflows | Bloc        |
+| Forms, auth, wizards   | Bloc        |
+| Feature modules        | Bloc        |
+
+---
+
+## Core Concepts
+
+| Concept | Description            |
+| ------- | ---------------------- |
+| Event   | User/system input      |
+| State   | Immutable UI state     |
+| Bloc    | Event → State mapper   |
+| Cubit   | State-only (no events) |
+
+---
+
+## Basic Bloc Setup
+
+### Event
+
+```dart
+sealed class CounterEvent {}
+
+final class CounterIncremented extends CounterEvent {}
+
+final class CounterDecremented extends CounterEvent {}
+```
+
+### State
+
+```dart
+class CounterState {
+  final int value;
+
+  const CounterState({required this.value});
+
+  CounterState copyWith({int? value}) {
+    return CounterState(value: value ?? this.value);
+  }
+}
+```
+
+### Bloc
+
+```dart
+import 'package:flutter_bloc/flutter_bloc.dart';
+
+class CounterBloc extends Bloc<CounterEvent, CounterState> {
+  CounterBloc() : super(const CounterState(value: 0)) {
+    on<CounterIncremented>((event, emit) {
+      emit(state.copyWith(value: state.value + 1));
+    });
+
+    on<CounterDecremented>((event, emit) {
+      emit(state.copyWith(value: state.value - 1));
+    });
+  }
+}
+```
+
+---
+
+## Cubit (Recommended for Simpler Logic)
+
+```dart
+class CounterCubit extends Cubit<int> {
+  CounterCubit() : super(0);
+
+  void increment() => emit(state + 1);
+  void decrement() => emit(state - 1);
+}
+```
+
+---
+
+## Providing Bloc to the Widget Tree
+
+```dart
+BlocProvider(
+  create: (_) => CounterBloc(),
+  child: const CounterScreen(),
+);
+```
+
+Multiple blocs:
+
+```dart
+MultiBlocProvider(
+  providers: [
+    BlocProvider(create: (_) => AuthBloc()),
+    BlocProvider(create: (_) => ProfileBloc()),
+  ],
+  child: const AppRoot(),
+);
+```
+
+---
+
+## Using Bloc in Widgets
+
+### BlocBuilder (UI rebuilds)
+
+```dart
+class CounterScreen extends StatelessWidget {
+  const CounterScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return BlocBuilder<CounterBloc, CounterState>(
+      buildWhen: (prev, curr) => prev.value != curr.value,
+      builder: (context, state) {
+        return Text(
+          state.value.toString(),
+          style: Theme.of(context).textTheme.displayLarge,
+        );
+      },
+    );
+  }
+}
+```
+
+---
+
+### BlocListener (Side Effects)
+
+```dart
+BlocListener<AuthBloc, AuthState>(
+  listenWhen: (prev, curr) => curr is AuthFailure,
+  listener: (context, state) {
+    if (state is AuthFailure) {
+      ScaffoldMessenger.of(context)
+          .showSnackBar(SnackBar(content: Text(state.message)));
+    }
+  },
+  child: const LoginForm(),
+);
+```
+
+---
+
+### BlocConsumer (Builder + Listener)
+
+```dart
+BlocConsumer<FormBloc, FormState>(
+  listener: (context, state) {
+    if (state.status == FormStatus.success) {
+      context.pop();
+    }
+  },
+  builder: (context, state) {
+    return ElevatedButton(
+      onPressed: state.isValid
+          ? () => context.read<FormBloc>().add(FormSubmitted())
+          : null,
+      child: const Text('Submit'),
+    );
+  },
+);
+```
+
+---
+
+## Accessing Bloc Without Rebuilds
+
+```dart
+context.read<CounterBloc>().add(CounterIncremented());
+```
+
+⚠️ **Never use `watch` inside callbacks**
+
+---
+
+## Async Bloc Pattern (API Calls)
+
+```dart
+on<UserRequested>((event, emit) async {
+  emit(const UserState.loading());
+
+  try {
+    final user = await repository.fetchUser();
+    emit(UserState.success(user));
+  } catch (e) {
+    emit(UserState.failure(e.toString()));
+  }
+});
+```
+
+---
+
+## Bloc + GoRouter (Auth Guard Example)
+
+```dart
+redirect: (context, state) {
+  final authState = context.read<AuthBloc>().state;
+
+  if (authState is Unauthenticated) {
+    return '/login';
+  }
+  return null;
+}
+```
+
+---
+
+## Testing Bloc
+
+```dart
+blocTest<CounterBloc, CounterState>(
+  'emits incremented value',
+  build: () => CounterBloc(),
+  act: (bloc) => bloc.add(CounterIncremented()),
+  expect: () => [
+    const CounterState(value: 1),
+  ],
+);
+```
+
+---
+
+## Best Practices (MUST FOLLOW)
+
+✅ Immutable states
+✅ Small, focused blocs
+✅ One feature = one bloc
+✅ Use Cubit when possible
+✅ Test all blocs
+
+❌ No UI logic inside blocs
+❌ No context usage inside blocs
+❌ No mutable state
+❌ No massive “god blocs”
+
+---
+
+## Quick Reference
+
+| Widget            | Purpose              |
+| ----------------- | -------------------- |
+| BlocBuilder       | UI rebuild           |
+| BlocListener      | Side effects         |
+| BlocConsumer      | Both                 |
+| BlocProvider      | Dependency injection |
+| MultiBlocProvider | Multiple blocs       |
+