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/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "ophion-otel-nodejs-example",
+  "version": "1.0.0",
+  "description": "Example Node.js app instrumented with OpenTelemetry for Ophion",
+  "main": "app.js",
+  "scripts": {
+    "start": "node app.js",
+    "trace": "node --require ./tracing.js app.js"
+  },
+  "dependencies": {
+    "@opentelemetry/api": "^1.7.0",
+    "@opentelemetry/auto-instrumentations-node": "^0.41.0",
+    "@opentelemetry/exporter-trace-otlp-http": "^0.47.0",
+    "@opentelemetry/resources": "^1.21.0",
+    "@opentelemetry/sdk-node": "^0.47.0",
+    "@opentelemetry/sdk-trace-node": "^1.21.0",
+    "@opentelemetry/semantic-conventions": "^1.21.0",
+    "express": "^4.18.2"
+  }
+}