Fix stagnation penalty floor to 0.01, never 0.0

Fix grader: clamp rewards to strictly (0.01, 0.99)

Fix server.py, expand tasks to 40, add tests, clean observation schema

fix initial reward from 0.0 to 0.001

restore SQLTask and SQLReward to models.py

use openenv base classes and fix yaml format to match working submissions

fix grader serialization and tasks endpoint

fix /tasks endpoint format for validator

Fix server entrypoint packaging and align environment docs

fix folder structure