HDA creation - traps and house rules

Staged by the 2026-11-08 round-2 baseline eval (ClaudeCode/evals/houdini-round2/ANALYSIS.md): with only the Houdini MCP, the model built, versioned and read back HDAs correctly 4/4; the skill was never opened. The tutorial body (create / version / organize / callbacks) is cut. What stays is what the eval measured or the house hit.

Use the MCP first: create_hda, update_hda, reload_hda, install_hda, get_hda_sections, set_hda_section_content, get_hda_info, list_hda_versions. Drop to hou.HDADefinition only for what they do not cover.

Traps (details and code in reference/versioning_and_verification.md)