Current implementation: String-based deduplication keys

fn push_error_dedup(&mut self, error: TypeCheckError) {
    let key = format!("UnknownType:{name}");
    // ...
}

It is better to migrate to ID-based deduplication for better performance and precision:

reported_errors: FxHashSet<(ErrorKind, u32)>  // (kind, node_id)

Benefits:

• More efficient than string allocation
• Distinguishes same name at different locations if needed
• Aligns with rust-analyzer's approach