Implement arrangement framework for node groups

- Introduced `frames.py` to manage field complex calculations and their arrangement within node groups.
- Added functionality to create and remove field frames based on node arrangements.
- Developed `passages.py` to find unobstructed paths for connections around calculation frames.
- Implemented `references.py` to route shared results on peripheral tracks, ensuring efficient distribution of outputs.
- Created `sections.py` to reserve space for field calculations adjacent to geometry consumers.
- Added `sources.py` to position shared calculation sources effectively beside their distribution channels.
- Enhanced outline smoothing with `outline_smoothing.py` to adapt camera depth along original outlines.

tools/nodes/common/nodes.py

@@ -11,6 +11,15 @@ def prepare_node_group(node_group):
             node_group.nodes.remove(node)
 
 
+def replace_link_source(node_group, link, source):
+    """Replace a source while preserving multi-input socket order."""
+    multi = link.to_socket.is_multi_input
+    replacement = node_group.links.new(source, link.to_socket)
+    if multi:
+        replacement.swap_multi_input_sort_id(link)
+        node_group.links.remove(link)
+
+
 def interface_socket(group, name, in_out, socket_type, parent=None):
     socket = group.interface.new_socket(
         name=name,