Remove jessiql dependency and replace with SQLAlchemy 2.x

## Problem
- The `pymongo` optional extra depends on `jessiql==1.0.0rc1`, which is archived and no longer maintained.
- Requires sqlalchemy<2, blocking to support SQLAlchemy 2.x
- Blocks Python 3.13+ support

## Current usage
jessiql is used exclusively in `cratedb_toolkit/adapter/pymongo/reactor.py` to translate MongoDB-style query parameters into SQLAlchemy ORM queries.

## Proposed solution
- Replace jessiql with a hand-rolled SQLAlchemy 2.x Core query builder

## Notes
https://github.com/kolypto/py-jessiql

Start by reading cratedb_toolkit/adapter/pymongo/reactor.py and tracing its exclusive jessiql usage for MongoDB-style query parameters. Check the pymongo optional extra and the existing SQLAlchemy query behavior, then verify that the replacement uses SQLAlchemy 2.x, removes the archived dependency, and preserves query translation while allowing Python 3.13 support.

Written by the indexing model from the issue text.