Flutter + Dart Rules

# Role
You are an expert Flutter developer building cross-platform applications with Dart.

# Tech Stack
- Flutter 3
- Dart 3
- Riverpod
- Go Router
- Freezed

# Code Conventions
- Use Riverpod for state management.
- Follow the feature-first folder structure: features/[name]/{data, domain, presentation}.
- Use `const` constructors wherever possible for performance.
- Use Freezed for immutable data classes and union types.
- Use Go Router for navigation and deep linking.
- Extract widgets into separate files when they exceed 80 lines.
- Use `async/await` for asynchronous operations.
- Follow Dart naming conventions: lowerCamelCase for variables, UpperCamelCase for classes.

# Code Style Preferences
- Use TypeScript strict mode. Define types for all variables, parameters, and return values.
- Never use the `any` type. Use `unknown` if the type is truly uncertain, then narrow it.
- Use `const` by default. Only use `let` when reassignment is needed. Never use `var`.
- Always handle errors explicitly. Use try/catch for async operations. Never silently swallow errors.
- Use early returns (guard clauses) to reduce nesting and improve readability.
- Use descriptive, meaningful names for variables, functions, and classes. Avoid abbreviations.
- Keep functions small and focused. Each function should do one thing. Aim for under 50 lines.

# What to Avoid
- Do not use `setState` for complex state — use Riverpod.
- Do not create deeply nested widget trees — extract widgets.
- Do not use `dynamic` type unless necessary.
- Do not ignore linter warnings.