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/arrangement/frames.py

@@ -0,0 +1,58 @@
+"""Frame complex field calculations by their consuming inputs."""
+
+from .flow import origin_socket
+
+FRAME_PADDING = 32
+FRAME_HEADING = 48
+FRAME_MIN_NODES = 12
+
+
+def remove_field_frames(node_group):
+    """Detach generated containers before calculating absolute positions again."""
+    frames = {node for node in node_group.nodes if node.get("arrangement_frame")}
+    for node in node_group.nodes:
+        if node.parent in frames:
+            position = tuple(node.location_absolute)
+            node.parent = None
+            node.location = position
+    for frame in frames:
+        node_group.nodes.remove(frame)
+
+
+def create_field_frames(node_group, bodies, core):
+    """Keep a complex calculation and its internal wire passages in one frame."""
+    for members, (left, right, top, bottom) in bodies:
+        if sum(node.bl_idname not in {"NodeGroupInput", "NodeReroute"} for node in members) < FRAME_MIN_NODES:
+            continue
+        members = set(members)
+        outlets = [link for node in members for socket in node.outputs for link in socket.links
+                   if link.to_node not in members]
+        targets = []
+        pending = list(outlets)
+        visited = set()
+        while pending:
+            link = pending.pop()
+            if link.to_node in core:
+                targets.append(link)
+            elif link.to_node not in visited:
+                visited.add(link.to_node)
+                pending.extend(edge for socket in link.to_node.outputs for edge in socket.links)
+        target = min(targets, key=lambda link: (link.to_node.location_absolute.x,
+                                               link.to_node.name, link.to_socket.name), default=None)
+        pending = {node for node in node_group.nodes if node.bl_idname == "NodeReroute"
+                   and node.get("arrangement_branch") and origin_socket(node.outputs[0]).node in members}
+        while ready := {node for node in pending if all(link.to_node in members for link in node.outputs[0].links)}:
+            members.update(ready)
+            pending.difference_update(ready)
+        frame = node_group.nodes.new("NodeFrame")
+        frame["arrangement_frame"] = True
+        frame.name = f"{target.to_node.name} · {target.to_socket.name}" if target else "Field Calculation"
+        frame.label = frame.name
+        frame.shrink = False
+        frame.location = (left - FRAME_PADDING, top + FRAME_HEADING)
+        frame.width = right - left + FRAME_PADDING * 2
+        frame.height = top - bottom + FRAME_HEADING + FRAME_PADDING
+        frame.use_custom_color = True
+        frame.color = (0.12, 0.16, 0.18)
+        for node in members:
+            node.parent = frame