Problem

The Quick Start example in README uses struct-update syntax when constructing a SearchRequest:

let response = mem.search(SearchRequest {
    query: "planning".into(),
    top_k: 10,
    snippet_chars: 200,
    ..Default::default()
})?;

However, SearchRequest does not implement Default, so this code fails to compile with:

error[E0277]: the trait bound `SearchRequest: Default` is not satisfied

Reported in #221.

Fix

Add an explicit Default implementation for SearchRequest with sensible values:

• query: empty String (callers override via struct-update)
• top_k: 10
• snippet_chars: 200
• all optional / flag fields: None / false / enum defaults

This makes the README Quick Start compile without changes, and gives library users the ergonomic struct-update pattern they already expect.

Testing

The change is purely additive — a new impl Default block. Existing code is unaffected. The fix can be verified with:

let _ = SearchRequest { query: "hello".into(), ..Default::default() };