Add OSS alpha readiness commands

[rlaope]

Summary

• Add loop doctor for local readiness checks covering Node.js, git, npm, repo boundary, package metadata, and optional Codex/Claude CLI availability.
• Add read-only loop demo examples for first-run, explicit-agent, and dry-run follow-up workflows.
• Add npm run verify as the local and CI quality gate, preserving package-content validation in scripts/verify-package.mjs.
• Update README, roadmap, contributing, PR template, and tests for the new public-alpha surface.

Verification

• node bin/loop.js doctor --expected-root /Users/rlaope/Desktop/khope/loop
• node bin/loop.js demo
• git diff --check
• npm run verify

Review

• Code-review pass found one pre-commit blocker: new files were untracked. Fixed by staging scripts/verify-package.mjs, src/core/demo.js, and src/core/doctor.js.
• Architecture pass cleared the read-only/local-only scope for doctor/demo.