feat: add observability with OpenTelemetry Spring Boot Starter

[adityamparikh]

Summary

• Add OpenTelemetry observability support using the official opentelemetry-spring-boot-starter
• Integrate LGTM stack (Loki, Grafana, Tempo, Mimir) via Docker Compose for local development
• Add @Observed annotation to service classes for distributed tracing
• Configure Prometheus metrics endpoint for scraping

Changes

• build.gradle.kts: Add OpenTelemetry instrumentation BOM and Spring Boot starter, Micrometer Prometheus registry
• compose.yaml: Add LGTM service (grafana/otel-lgtm) for observability backend
• application-http.properties: Add OTEL configuration with gRPC protocol on port 4317
• logback-spring.xml: Add profile-specific logging (http/stdio/test profiles)
• Service classes: Add @Observed annotation for automatic span creation

Observability Stack

Signal	Protocol	Destination
Traces	OTLP/gRPC	Tempo
Metrics	Prometheus scrape	Mimir
Logs	OTLP	Loki

Access Grafana at http://localhost:3000 after starting the application in HTTP mode.

Test plan

• Start application with --spring.profiles.active=http
• Verify Docker Compose starts LGTM container automatically
• Access Grafana at http://localhost:3000
• Execute MCP tool calls and verify traces appear in Tempo
• Verify metrics are available at /actuator/prometheus
• Check logs appear in Loki

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