fix(delete_by_expiry): add missing bind parameter and handle string-to-number conversion

[NCura]

Problem

The delete_by_expiry function had two bugs that prevented it from cleaning up expired sessions:

1. Missing bind parameter: The SELECT query referenced $expires but never bound it, causing the query
   to return empty results
2. Type mismatch: When sessionexpires is stored as a string (e.g., '1760389854'), the comparison
   sessionexpires < $expires fails because SurrealDB compares string-to-number incorrectly

Solution

• Added the missing .bind(("expires", now)) to the SELECT query
• Wrapped sessionexpires with type::number() in both SELECT and DELETE queries to ensure proper numeric comparison

Testing

Tested in my project with thousands of expired sessions that were not being cleaned up. After the fix, all expired sessions are now properly deleted.

Optional Further Optimization

This fix maintains the current two-query approach (SELECT + DELETE). However, SurrealDB supports RETURN BEFORE in DELETE statements, which would allow combining both queries into one:

let mut res = self.connection
    .query("DELETE type::table($table_name)
           WHERE sessionexpires = NONE OR type::number(sessionexpires) < $expires
           RETURN BEFORE;")
    .bind(("table_name", table_name.to_string()))
    .bind(("expires", now))
    .await
    .map_err(|err| DatabaseError::GenericSelectError(err.to_string()))?;

let records: Vec<SessionRecord> = res.take(0).map_err(|err| DatabaseError::GenericSelectError(err.to_string()))?;
let ids: Vec<String> = records.into_iter().map(|r| r.sessionid).collect();

Let me know if you'd like me to include this optimization in the PR as well.

[genusistimelord]

thank you for catching and fixing this issue.

[genusistimelord]

if that Optimization is indeed an optimizations I don't see why you would not just include it?

[NCura]

I didn't want to mix the fix with the optimization in this PR, and I was not sure if there was a good reason to separate the query into SELECT + DELETE. I've now included the change in the last commit.

[genusistimelord]

approved the change. thank you