Issue 6: `retry_count` is incremented inside the validator, not the generator

[sanjaigridsandguides]

Problem

• validate_node does new_retry_count = state["retry_count"] + 1.
• This means the counter counts validation attempts, not generation attempts.
• The terminology "retry" usually refers to retried generations.

Impact

• Reader/maintainer confusion. The semantics of iterationCount in output.json are ambiguous.
• If the validator ever raises before the increment line, retries are silently lost.

Required Fix

• Increment the counter in generate_node (one place, one meaning).
• Rename to attempt_count if it represents attempts, not retries.