build(moon): slim root task surface

[jmgilman]

Summary

• collapse the root Moon command surface from 24 tasks to 8 maintainer-facing tasks
• add a single root:check task for formatting, lint, generated drift, Helm validation, and Chainsaw manifest linting while keeping root:test separate
• remove the dev stack smoke path and move longer deploy/e2e/check bodies into scripts
• update CI, README, DELETE_ME, AGENTS, Tilt, and Chainsaw cleanup references

Testing

• moon run root:check --summary minimal
• moon run root:test --summary minimal
• moon run root:test-e2e --summary minimal
• bash -n scripts/check.sh scripts/deploy.sh scripts/test-e2e.sh scripts/undeploy.sh
• git diff --check