Function mark_starred 

pub async fn mark_starred(
    pool: &SqlitePool,
    did: &str,
    entry_id: i64,
    starred: bool,
) -> Result<bool>

Star/unstar a single entry for a DID (upsert, preserving read).

AUTHORIZED per-DID like mark_read: only touches an entry the caller subscribes to. Returns true if a row was written, false if did does not subscribe (→ 404 at the web layer).