GitHub Copilot Rust Guidelines

# GitHub Copilot Rust Configuration

## Ownership Patterns
```rust
// Prefer borrowing
fn process(data: &[u8]) -> Result<(), Error> {
    // Read-only access
    Ok(())
}

// Mutable borrowing
fn modify(data: &mut Vec<u8>) {
    data.push(0);
}
```

## Error Handling
```rust
use thiserror::Error;

#[derive(Error, Debug)]
pub enum AppError {
    #[error("Not found: {0}")]
    NotFound(String),
    #[error(transparent)]
    Database(#[from] sqlx::Error),
}

fn get_user(id: &str) -> Result<User, AppError> {
    users.get(id)
        .cloned()
        .ok_or_else(|| AppError::NotFound(id.into()))
}
```

## Async Patterns
```rust
use tokio;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let result = fetch_data().await?;
    println!("{:?}", result);
    Ok(())
}
```

## Cargo.toml Dependencies
- Use specific versions
- Document why each dependency is needed
- Minimize dependencies when possible