feat: Add OpenTelemetry OTLP HTTP receiver

- Add POST /v1/traces endpoint for OTLP JSON trace ingestion
- Convert OTLP spans to internal format and save to PostgreSQL
- Manual JSON parsing (no Go 1.24 dependencies)
- Add Node.js instrumentation example with Express
- Add Python instrumentation example with Flask
- Auto-instrumentation support for both languages

examples/otel-python/tracing.py

@@ -0,0 +1,84 @@
+"""
+═══════════════════════════════════════════════════════════
+🔭 OpenTelemetry Tracing Setup for Ophion
+═══════════════════════════════════════════════════════════
+
+This module initializes OpenTelemetry tracing and sends spans
+to Ophion's OTLP HTTP endpoint.
+
+Usage:
+    from tracing import init_tracing, get_tracer
+    init_tracing()
+    tracer = get_tracer()
+"""
+
+import os
+from opentelemetry import trace
+from opentelemetry.sdk.trace import TracerProvider
+from opentelemetry.sdk.trace.export import BatchSpanProcessor
+from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
+from opentelemetry.sdk.resources import Resource, SERVICE_NAME, SERVICE_VERSION, DEPLOYMENT_ENVIRONMENT
+
+# Global tracer
+_tracer = None
+
+
+def init_tracing(service_name: str = None) -> None:
+    """
+    Initialize OpenTelemetry tracing with OTLP HTTP exporter.
+    
+    Args:
+        service_name: Name of the service (default: from env or 'python-example')
+    """
+    global _tracer
+    
+    # Get configuration from environment
+    otlp_endpoint = os.getenv('OTEL_EXPORTER_OTLP_ENDPOINT', 'http://localhost:8080')
+    service = service_name or os.getenv('OTEL_SERVICE_NAME', 'python-example')
+    environment = os.getenv('DEPLOYMENT_ENVIRONMENT', 'development')
+    
+    # Create resource with service info
+    resource = Resource.create({
+        SERVICE_NAME: service,
+        SERVICE_VERSION: '1.0.0',
+        DEPLOYMENT_ENVIRONMENT: environment,
+    })
+    
+    # Create tracer provider
+    provider = TracerProvider(resource=resource)
+    
+    # Configure OTLP HTTP exporter
+    # Note: endpoint should be base URL, SDK adds /v1/traces
+    exporter = OTLPSpanExporter(
+        endpoint=f"{otlp_endpoint}/v1/traces",
+        # headers={"Authorization": f"Bearer {os.getenv('OPHION_API_KEY', '')}"},
+    )
+    
+    # Add batch processor for efficient sending
+    processor = BatchSpanProcessor(exporter)
+    provider.add_span_processor(processor)
+    
+    # Set as global tracer provider
+    trace.set_tracer_provider(provider)
+    
+    # Create tracer
+    _tracer = trace.get_tracer(__name__)
+    
+    print(f"🔭 OpenTelemetry tracing initialized")
+    print(f"   Service: {service}")
+    print(f"   Endpoint: {otlp_endpoint}/v1/traces")
+
+
+def get_tracer():
+    """Get the initialized tracer."""
+    global _tracer
+    if _tracer is None:
+        init_tracing()
+    return _tracer
+
+
+def shutdown():
+    """Gracefully shutdown the tracer provider."""
+    provider = trace.get_tracer_provider()
+    if hasattr(provider, 'shutdown'):
+        provider.shutdown()