Fix pipeline 0.0 scoring override, resolve test floating-point flakiness, and add readable CLI output for inference.py

added graders and rewards

add 59 tests for the LLM modules — all run offline, no API needed

test(graders): add programmatic_grader tests — structure, score range, letter grade

test(graders): add hard_grader tests — breakthrough bonus and repetitive penalty

test(graders): add medium_grader tests — diversity scores higher than uniform strategies

test(graders): add easy_grader tests — empty, good, bad episode and range check

test(environment): add injection tests — custom reward_computer and llm_pipeline are called

test(environment): add framing sanitization tests for script and javascript injection

test(environment): add guard tests — step without reset raises, step past max_turns raises

test(environment): add step() tests — turn increment, history append, result shape

test(environment): add reset() tests — observation shape, history clear, unique ids

chore(tests): add tests package __init__.py