feat: api key authentication (#291)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/internal/utils/hash_util.go

@@ -0,0 +1,11 @@
+package utils
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+)
+
+func CreateSha256Hash(input string) string {
+	hash := sha256.Sum256([]byte(input))
+	return hex.EncodeToString(hash[:])
+}