feat(skills): introduce script authoring methodology

[Ldsystem]

Summary

• Convert the script-instruction rule into the compact wb-create-script skill.
• Separate deterministic mechanics, supplied policy, and agent judgment.
• Preserve workspace utility safety in a conditional reference and update direct consumers.
• No production runtime behavior changes; no new acceptance gates.

Validation

• 48 focused rule/skill contract tests passed.
• System skill validation and WorkBundle skill/rule validation passed.
• Independent baseline and four forward scenarios exercised responsibility and scope decisions.
• Full canonical local CI is running; hosted CI will validate this exact PR head.

Scope

This addresses part of WOR-110 instruction methodology only; it does not close WOR-110 or implement its resource/layout migration.