Function fts_search 

pub fn fts_search(
    conn: &Connection,
    query: &str,
    namespace: &str,
    memory_type: Option<&str>,
    limit: usize,
) -> Result<Vec<MemoryRow>, AppError>

Executes an FTS5 search against fts_memories with query preprocessing.

Technical separators in the query are converted to phrase + prefix OR expressions so compound terms like graphrag-precompact.sh match correctly.

Errors

Returns Err(AppError::Database) on any rusqlite failure.