refactor(cli): rebuild create-spawn-dock on effect-template workspace

[skulidropek]

Summary

• rebuild create-spawn-dock as an effect-template-style TypeScript workspace with packages/app
• remove embedded template-nextjs-overlay from the CLI repo
• keep only bootstrap logic that clones SpawnDock/tma-project and writes project-specific runtime files
• preserve /mcp/sse generation and GitHub-based npx fallback

Validation

• pnpm install
• pnpm typecheck
• pnpm test
• pnpm build
• npm pack --dry-run
• local smoke: compiled CLI bootstraps a project against local api and writes /mcp/sse + tonconnect-manifest.json