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

cmd/server/main.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/bigtux/ophion/internal/auth"
+	"github.com/bigtux/ophion/internal/otel"
 	"github.com/bigtux/ophion/internal/security"
 	"github.com/gofiber/fiber/v2"
 	"github.com/gofiber/fiber/v2/middleware/cors"
@@ -271,6 +272,19 @@ func (s *Server) setupRoutes() {
 	// Security headers
 	s.app.Use(security.SecurityHeaders())
 
+	// ═══════════════════════════════════════════════════════════
+	// 🔭 OTLP HTTP Receiver (OpenTelemetry Protocol)
+	// ═══════════════════════════════════════════════════════════
+	// Standard OTLP endpoint - can be public or protected based on config
+	otlpReceiver := otel.NewOTLPReceiver(s.db)
+	
+	// OTLP routes (public by default for easy integration)
+	// For production, consider adding auth middleware
+	s.app.Post("/v1/traces", otlpReceiver.HandleTraces)
+	
+	// Also support the full path that some SDKs use
+	s.app.Post("/v1/traces/", otlpReceiver.HandleTraces)
+
 	// API v1
 	api := s.app.Group("/api/v1")