Adds the composable monorepo template system that generates project skeletons
with pluggable components (service, worker, app-react, app-astro, cli).
Key changes:
- Monorepo skeleton templates with shared pkg/, scripts/, and git hooks
- Component templates (service, worker, app-react, app-astro, cli) with
Dockerfiles, CI steps, and component.yaml manifests
- Component domain model with validation and dependency resolution
- Component handler endpoints for CRUD and composition
- Template provider extended with BuildComposableProject and component assembly
- Deployer extended with composable project deployment support
- Handler timeout constants (TimeoutFastLookup through TimeoutLongRunning)
- envutil package for centralized env var reads with defaults
- api.DecodeJSON helper for standardized request body decoding
- Standardized response helpers (WriteBadRequest, WriteNotFound, etc.)
- Replaced fullstack-app cookbook with composable-app cookbook
- Hardened handler timeouts, logging, and error responses across all handlers
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
