Add CLAUDE.md documentation

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Development Commands
+
+### Building and Testing
+- `make all` - Default build target that builds all components
+- `./mage build:all` - Alternative build command via mage
+- `make go-test` - Run unit tests for internal/, cmd/, pkg/, and controllers/ packages
+- `make test-integration` - Run integration tests against current $KUBECONFIG cluster
+- `make test-integration-short` - Run integration tests without operator setup/teardown
+- `make test-integration-local` - Setup local dev environment and run full integration suite
+- `make tidy` - Run go mod tidy (used by pre-commit hooks)
+
+### Development Environment
+- `make dev-setup` - Setup kind cluster with OLM and OpenShift Console for out-of-cluster development
+- `make test-setup` - Complete setup: kind cluster + OLM + Console + compile + build containers + install operator
+- `make run-addon-operator-manager` - Run operator out-of-cluster (requires dev-setup first)
+- `make setup-addon-operator-crds` - Install CRDs into cluster
+- `export KUBECONFIG=$PWD/.cache/dev-env/kubeconfig.yaml` - Use local kind cluster
+
+### Code Quality
+- `make container-generate` - Generate CRDs via containerized controller-gen
+- `make container-lint` - Run linters via containerized golangci-lint
+- `make generate-bundle` - Generate OLM bundle after modifying operator manifests
+
+### Environment Variables for Testing
+- `ENABLE_WEBHOOK=true/false` - Deploy webhook server with admission webhooks
+- `WEBHOOK_PORT=<PORT>` - Port for webhook server
+- `ENABLE_API_MOCK=true/false` - Deploy mock OCM API server for UpgradePolicy testing
+- `ENABLE_MONITORING=true/false` - Deploy kube-prometheus monitoring stack
+
+## Architecture Overview
+
+### Core Components
+- **Addon Operator**: Kubernetes controller that orchestrates addon lifecycles on managed OpenShift clusters
+- **Custom Resources**: Three main CRDs - Addon, AddonInstance, and AddonOperator
+- **Controllers**: Separate controller packages for each CRD in `controllers/` directory
+- **Webhooks**: Admission webhooks in `internal/webhooks/` for validation and mutation
+
+### Project Structure
+- `api/v1alpha1/` - Kubernetes API definitions and CRD types
+- `controllers/` - Controller implementations for each custom resource
+- `internal/` - Internal packages including metrics, OCM client, feature toggles, webhooks
+- `cmd/` - Entry points for different operator components
+- `deploy/` - Production-grade Kubernetes manifests
+- `integration/` - Integration test suites
+- `magefiles/` - Mage build automation scripts
+
+### Key Internal Packages
+- `internal/ocm/` - OCM (OpenShift Cluster Manager) API client integration
+- `internal/metrics/` - Prometheus metrics collection and reporting
+- `internal/featuretoggle/` - Feature flag management system
+- `internal/webhooks/` - Kubernetes admission webhook implementations
+
+### Dependencies and Tooling
+- Uses Boilerplate project for standardized tooling and conventions
+- Built with controller-runtime framework
+- Integrates with OLM (Operator Lifecycle Manager)
+- Supports both podman and docker container runtimes
+- Pre-commit hooks enforce code quality (go-fmt, go-mod-tidy)
+
+### Testing Strategy
+- Unit tests cover internal logic and controller business logic
+- Integration tests run against real Kubernetes clusters via kind
+- Supports both in-cluster and out-of-cluster development workflows
+- Mock OCM API server available for testing upgrade policies