Initialize PRISM student publication workflow

[mnarayan]

Summary

• replace template placeholders and links with PRISM 2026 publication metadata
• rewrite README, quickstart, and contribution guidance for student branches and reviewed pull requests
• add shared AGENTS.md and CLAUDE.md publishing guidance without repo-local skill duplication
• validate publication metadata and stale links in GitHub Actions
• preserve the existing Warm Journal default and Technical Notebook option

Verification

• 46 pytest tests passed
• Ruff check and format check passed
• CITATION.cff schema validation passed
• Warm Journal and Technical Notebook rendered successfully
• git diff --check passed