Default start image version from CLI package

[douglance]

Summary

• derive the CLI version and default testnode start image version from apps/cli/package.json
• remove duplicated release versions from normal config/testnodes.json entries while preserving named overrides like fast
• make the CI resolver fall back to the same package-derived image version and document bare pnpm dev start

Tests

• pnpm vitest run apps/cli/test/start.test.ts test/resolve-testnode.test.ts test/version-source.test.ts
• pnpm typecheck
• pnpm build
• pnpm test:run
• pnpm lint
• built CLI smoke: node apps/cli/dist/index.js --version and default start resolution