Builder Pattern

Use builder pattern for complex configuration:

#[derive(Debug, Clone, Default)]
pub struct Config {
    timeout: Duration,
    retries: u32,
}

impl Config {
    #[must_use]
    pub const fn new() -> Self {
        Self {
            timeout: Duration::from_secs(30),
            retries: 3,
        }
    }

    #[must_use]
    pub const fn with_timeout(mut self, timeout: Duration) -> Self {
        self.timeout = timeout;
        self
    }

    #[must_use]
    pub const fn with_retries(mut self, retries: u32) -> Self {
        self.retries = retries;
        self
    }
}