Document existing /health endpoint implementation in Go

[Copilot]

After investigating the request to add a /health endpoint to the Go implementation, I discovered that the endpoint is already fully implemented and working correctly.

Current Implementation

The /health endpoint in the Go implementation (src/go/cmd/lamp-control-api/main.go) already meets all the specified requirements:

• ✅ Available at /health (not /v1/health)
• ✅ Returns HTTP 200 OK status when healthy
• ✅ Responds with JSON: {"status": "ok"}
• ✅ Comprehensive test coverage (unit and integration tests)
• ✅ Documented in README.md

Implementation Details

func healthHandler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(http.StatusOK)
    
    response := HealthResponse{Status: "ok"}
    json.NewEncoder(w).Encode(response)
}

The endpoint is properly:

• Separated from OpenAPI validation middleware
• Added directly to the Chi router before /v1 routes
• Used in CI pipelines for health checks (Kotlin and PHP workflows)
• Tested with both unit tests (TestHealthHandler) and integration tests (TestHealthEndpointIntegration)

Verification

All tests pass successfully, including the health endpoint tests:

$ make test
=== RUN   TestHealthHandler
--- PASS: TestHealthHandler (0.00s)
=== RUN   TestHealthEndpointIntegration
--- PASS: TestHealthEndpointIntegration (0.00s)

The endpoint is already being used across multiple language implementations (TypeScript, Python, Kotlin, PHP) and is consistently implemented.

Fixes #175.

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