Implement OpenTelemetry for TypeScript service

[davideme]

Overview

Implement the OpenTelemetry integration for the TypeScript (Fastify + Prisma) service as specified in src/typescript/docs/adr/008-opentelemetry.md.

Parent issue: #14

Tasks

• Add required npm packages (@opentelemetry/api, @opentelemetry/sdk-node, @opentelemetry/auto-instrumentations-node, @opentelemetry/exporter-trace-otlp-grpc, @opentelemetry/exporter-metrics-otlp-grpc, @prisma/instrumentation)
• Create SDK init file loaded before app code (no-op when OTEL_EXPORTER_OTLP_ENDPOINT is absent)
• Configure FastifyInstrumentation + HttpInstrumentation for inbound HTTP traces
• Configure UndiciInstrumentation for outbound HTTP traces
• Configure PrismaInstrumentation for database traces
• Inject trace context into Fastify request logs (trace.getActiveSpan())
• Verify metrics baseline: http.server.request.duration, http.server.active_requests
• Set resource attributes: service.name=lamp-control-api-typescript, service.version, deployment.environment
• Ensure W3C TraceContext + Baggage propagation is enabled
• Add/update tests to verify instrumentation wires up correctly

Instrumentation summary

Signal	Mechanism	Type
Traces – Inbound HTTP	instrumentation-fastify + instrumentation-http	Config only
Traces – Outbound HTTP	instrumentation-http / instrumentation-undici	Config only
Traces – Database	@prisma/instrumentation	Config only
Metrics – HTTP server	instrumentation-http (auto-emitted)	Config only
Logs	Manual Fastify onRequest hook + OTel API	Custom code

Acceptance criteria

• SDK is a no-op when OTEL_EXPORTER_OTLP_ENDPOINT is not set
• All three pillars (traces, metrics, logs) emit data when collector is configured
• Existing tests continue to pass

[davideme]

Structured Logging Requirement

This issue should explicitly include structured (JSON) logging configuration as part of the implementation:

• Pino JSON output: Ensure Fastify is configured with Pino in JSON mode (not pretty-print) for production. fastify({ logger: true }) defaults to JSON, but this should be explicitly documented in the implementation task.
• Trace context fields: The custom onRequest hook that injects trace context must add trace_id and span_id as top-level JSON fields in Pino log records (not just as text), so log aggregators can correlate logs with traces even without an OTel collector.
• Log level via env: Ensure LOG_LEVEL (or OTEL_LOG_LEVEL) controls Pino's log level.

Structured logging should work correctly even when OTEL_EXPORTER_OTLP_ENDPOINT is absent (i.e., JSON logs with trace context injection still function in no-op mode).