Sync AGENTS.md, CLAUDE.md, and .claude/rules from updated project_rules
templates: workplan-first session protocol, legacy terminology footnote,
and GET /workplans/ examples.
Rewrite INTENT.md as the sand-boxer meta-framework charter (OpenRouter-style
sandbox API, extensions, payments, Coulomb sibling boundaries). Add research
under research/, update SCOPE.md, bootstrap workplans SAND-WP-0001/0002, and
State Hub integration files from the bootstrap pass.