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/requirements.txt

@@ -0,0 +1,15 @@
+# OpenTelemetry SDK and API
+opentelemetry-api>=1.22.0
+opentelemetry-sdk>=1.22.0
+
+# OTLP HTTP Exporter
+opentelemetry-exporter-otlp-proto-http>=1.22.0
+
+# Auto-instrumentation
+opentelemetry-instrumentation>=0.43b0
+opentelemetry-instrumentation-flask>=0.43b0
+opentelemetry-instrumentation-requests>=0.43b0
+
+# Web framework
+flask>=3.0.0
+requests>=2.31.0