refactor nodes into standalone file

backend/nodes/coordinate.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+from backend.node_registry import register_node
+
+
+@register_node(display_name="Coordinate")
+class Coordinate:
+    """Provide a fractional (x, y) point for use with Cross Section or other nodes."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "x": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 1.0, "step": 0.01}),
+                "y": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 1.0, "step": 0.01}),
+            }
+        }
+
+    RETURN_TYPES = ("COORD",)
+    RETURN_NAMES = ("point",)
+    FUNCTION = "process"
+
+    DESCRIPTION = "Output a fractional (x, y) coordinate pair in [0, 1]."
+
+    def process(self, x: float, y: float) -> tuple:
+        return ((float(x), float(y)),)