refactor nodes into standalone file

backend/nodes/number.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+from backend.node_registry import register_node
+
+
+@register_node(display_name="Number")
+class Number:
+    """Provide a fixed scalar value that can feed FLOAT or INT widget sockets."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": ("FLOAT", {"default": 0.0, "step": 0.01}),
+            }
+        }
+
+    RETURN_TYPES = ("FLOAT",)
+    RETURN_NAMES = ("value",)
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Output a fixed numeric value. "
+        "When connected to FLOAT inputs the exact value is used; "
+        "INT inputs round to the nearest integer at execution time."
+    )
+
+    def process(self, value: float) -> tuple:
+        return (float(value),)