Standardize skill surfaces and baseline-source docs

[medhatgalal]

Summary

• move historical prompt fidelity baselines into repo-resident sources/ssot-baselines/
• persist baseline metadata and validation matrices through UAC descriptors and generated resources
• standardize direct deployment on skills/<slug>/SKILL.md and remove stale command/prompt direct-surface logic
• realign README/docs/contributing/release docs with the current wrapper-based workflow and release order

Validation

• pytest -q
• /opt/homebrew/bin/python3.11 scripts/build-surfaces.py
• /opt/homebrew/bin/python3.11 scripts/validate-surfaces.py --strict
• python3 scripts/smoke-clis.py
• scripts/deploy-surfaces.sh --dry-run --cli all
• scripts/package-surfaces.sh --version v1.4.7

Notes

• local smoke reports a non-blocking Gemini discovery warning from the installed Gemini CLI, but the generated surface/filesystem checks pass
• release packaging was smoke-tested locally; final publish should happen from merged main once hosted CI is green