chore(install): omit development dependencies

[blckbx]

Summary

• use npm install --omit=dev for local plugin deployment and its smoke test
• replace mutable CI and release installs with deterministic npm ci
• document the development-only OpenClaw SDK baseline and enforce install commands with contract tests

Validation

• npm test — 190 tests passed
• npm run lint
• npm run typecheck
• npm run format:check
• npm run package:validate
• npm run sdk:baseline
• npm run smoke:built
• npm run smoke:package
• npm run smoke:install under supported Node 24.15.0
• npm run package:dry-run
• npm run audit — zero production/deploy-host findings; 11 findings remain isolated to the pinned development-only OpenClaw 2026.6.1 SDK baseline