fix: remove default pixel-style locks from row prompts

[lamb670]

Summary

• stop the default generation prompt from locking logical pixel density, a fixed palette, or a hard-edged sprite look
• let the attached layout guide carry slot and safe-area geometry instead of restating exact source pixel dimensions as creative requirements
• preserve identity, frame-count, chroma-key, clipping, extraction, and opt-in pixel-art contracts

Tests

• pytest tests/curate tests/gen -q -o timeout_method=thread (435 passed on Windows with UTF-8 mode)

[lamb670]

This adjustment is project-specific and will be handled in lamb670/idle-game instead. Closing this upstream PR.