Add optional OpenTelemetry tracing and metrics

[singhvishalkr]

Summary

This PR adds OpenTelemetry instrumentation for observability into agent and multi-agent workflow executions, addressing issue #1199.

Key features:

• Optional tracing that activates only when SWARMS_OTEL_ENABLED=true and dependencies are installed
• Automatic span creation for Agent.run(), SwarmRouter.run(), SequentialWorkflow.run(), and ConcurrentWorkflow.run()
• Metrics collection for run counts, durations, and errors
• Graceful degradation when OTEL packages aren't installed

Span attributes captured:

• Agent: name, id, model, max_loops, has_image, duration, status
• Swarm: name, id, type, agent_count, duration, status

Configuration via environment variables:

• SWARMS_OTEL_ENABLED - Enable/disable tracing (default: false)
• OTEL_SERVICE_NAME - Service name (default: swarms)
• OTEL_EXPORTER_OTLP_ENDPOINT - OTLP collector endpoint

Changes

• Add swarms/telemetry/otel.py with tracing context manager, decorators, and metrics
• Integrate tracing into Agent, SwarmRouter, SequentialWorkflow, ConcurrentWorkflow
• Add optional opentelemetry-* dependencies to pyproject.toml
• Add documentation at docs/swarms/telemetry/opentelemetry.md
• Add example at examples/telemetry/otel_tracing_example.py
• Add unit tests at ests/telemetry/test_otel.py

Test plan

• Verify syntax compilation passes (done locally)
• Run with OTEL disabled - no overhead or errors
• Run with OTEL enabled + Jaeger - traces appear correctly
• Run existing tests to ensure no regressions

Closes #1199

---

📚 Documentation preview 📚: https://swarms--1615.org.readthedocs.build/en/1615/

[github-actions]

Hello there, thank you for opening an PR ! 🙏🏻 The team was notified and they will get back to you asap.