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.
+
+## Project Overview
+
+This is a Kubernetes operator that manages Splunk Universal Forwarder deployments. It creates DaemonSets that deploy Splunk forwarder pods on each node in the cluster to collect and forward logs to Splunk instances.
+
+## Key Architecture Components
+
+- **API Types**: `api/v1alpha1/splunkforwarder_types.go` - Defines the SplunkForwarder CRD with fields for image configuration, cluster ID, and input specifications
+- **Controllers**:
+  - `controllers/splunkforwarder/splunkforwarder_controller.go` - Main controller reconciling SplunkForwarder resources
+  - `controllers/secret/secret_controller.go` - Manages Splunk authentication secrets
+- **Kubernetes Resources**: `pkg/kube/` - Utilities for creating DaemonSets, ConfigMaps, Services, Volumes, and VolumeMounts
+- **Configuration**: Uses a "splunk-auth" secret containing `cacert.pem`, `server.pem`, `outputs.conf`, and `limits.conf`
+
+## Development Commands
+
+**Building and Testing:**
+```bash
+# Build the operator binary
+make go-build
+
+# Run unit tests
+make go-test
+
+# Run linting and validation
+make lint
+make validate
+
+# Build container image
+make docker-build
+
+# Build and push images (for releases)
+make build-push
+```
+
+**Local Development:**
+```bash
+# Required environment variables for local runs
+export OPERATOR_NAMESPACE=openshift-splunk-forwarder-operator
+export WATCH_NAMESPACE=""
+export OSDK_FORCE_RUN_MODE="local"
+```
+
+**Image Updates:**
+```bash
+# Update to latest forwarder image from upstream
+make image-update
+
+# Update to specific version/commit
+make SFI_UPDATE=<commit/branch> image-update
+
+# Update OLM templates with new image digests
+make image-digests
+```
+
+**Container Testing:**
+```bash
+# Run tests in boilerplate container
+make container-test
+
+# Run linting in container
+make container-lint
+```
+
+## Project Structure
+
+- Built with Operator SDK v1.21.0+ and Go 1.23+
+- Uses OpenShift boilerplate for standardized build/test/deploy workflows
+- Includes E2E tests in `test/e2e/`
+- FIPS-compliant builds supported via `FIPS_ENABLED=true`
+- Supports both Universal Forwarder and Heavy Forwarder deployments