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-nodejs/tracing.js

@@ -0,0 +1,52 @@
+// ═══════════════════════════════════════════════════════════
+// 🔭 OpenTelemetry Tracing Setup for Ophion
+// ═══════════════════════════════════════════════════════════
+//
+// This file initializes OpenTelemetry tracing and sends spans
+// to Ophion's OTLP HTTP endpoint.
+//
+// Usage: node --require ./tracing.js app.js
+
+const { NodeSDK } = require('@opentelemetry/sdk-node');
+const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-http');
+const { getNodeAutoInstrumentations } = require('@opentelemetry/auto-instrumentations-node');
+const { Resource } = require('@opentelemetry/resources');
+const { SemanticResourceAttributes } = require('@opentelemetry/semantic-conventions');
+
+// Configure the OTLP exporter to send to Ophion
+const traceExporter = new OTLPTraceExporter({
+  // Ophion OTLP endpoint - adjust host/port as needed
+  url: process.env.OTEL_EXPORTER_OTLP_ENDPOINT || 'http://localhost:8080/v1/traces',
+  headers: {
+    // Optional: add authorization if Ophion requires it
+    // 'Authorization': `Bearer ${process.env.OPHION_API_KEY}`,
+  },
+});
+
+// Create the SDK with auto-instrumentation
+const sdk = new NodeSDK({
+  resource: new Resource({
+    [SemanticResourceAttributes.SERVICE_NAME]: process.env.OTEL_SERVICE_NAME || 'nodejs-example',
+    [SemanticResourceAttributes.SERVICE_VERSION]: '1.0.0',
+    [SemanticResourceAttributes.DEPLOYMENT_ENVIRONMENT]: process.env.NODE_ENV || 'development',
+  }),
+  traceExporter,
+  instrumentations: [
+    getNodeAutoInstrumentations({
+      // Disable fs instrumentation to reduce noise
+      '@opentelemetry/instrumentation-fs': { enabled: false },
+    }),
+  ],
+});
+
+// Start the SDK
+sdk.start();
+console.log('🔭 OpenTelemetry tracing initialized - sending to Ophion');
+
+// Graceful shutdown
+process.on('SIGTERM', () => {
+  sdk.shutdown()
+    .then(() => console.log('OpenTelemetry SDK shut down'))
+    .catch((error) => console.error('Error shutting down SDK', error))
+    .finally(() => process.exit(0));
+});