add pxd headers for correct work

fixes definitions
can run until API call

Azaion.AI/annotation.pyx

@@ -0,0 +1,13 @@
+cdef class Detection:
+    def __init__(self, double x, double y, double w, double h, int cls):
+        self.x = x
+        self.y = y
+        self.w = w
+        self.h = h
+        self.cls = cls
+
+cdef class Annotation:
+    def __init__(self, bytes image_bytes, float time, list[Detection] detections):
+        self.image = image_bytes
+        self.time = time
+        self.detections = detections