Complete API handlers refactoring to eliminate type switching and use repository pattern consistently

internal/api/middleware.go

@@ -3,6 +3,7 @@ package api
 import (
 	"log"
 	"net/http"
+	"slices"
 	"strings"
 	"time"
 )
@@ -92,13 +93,7 @@ func CORSPreflightHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Check if origin is allowed
-	originAllowed := false
-	for _, allowed := range allowedOrigins {
-		if origin == allowed {
-			originAllowed = true
-			break
-		}
-	}
+	originAllowed := slices.Contains(allowedOrigins, origin)
 
 	if originAllowed {
 		w.Header().Set("Access-Control-Allow-Origin", origin)