Publish production Blender generation and editing pipelines

[cardenasmackessy175-ship-it]

Summary

• publish separate from-zero generation and existing-asset editing pipelines under skills/blender-pipeline
• curate the knowledge base through 2026-08-22 and make indexing manifest-bound
• replace private infrastructure and smoke-test residue with portable contract tests and Blender end-to-end tests
• add package validation and CI quality gates

Validation

• package completeness/sensitive/import/schema/link validator
• 47 unit and end-to-end tests, including Blender 5.1 execution
• Ruff lint and format checks
• Bandit, detect-secrets, pip-audit, package build/install, and independent staged-content audit