Split clearance: node-size for face detections, spacing-scaled for routing

Target-join and boundary-slot detection now use ResolveNodeSizeClearance
(node dimensions only), while under-node/proximity use
ResolveMinLineClearance (scales with NodeSpacing via ElkLayoutClearance).

Face slot gaps depend on node face geometry, not inter-node spacing.
Routing corridors should scale with spacing for visual breathing room.

Created sprint 008 for wider spacing robustness. NodeSpacing=50 still
fails on target-join (scoring/test detection mismatch needs investigation).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/__Libraries/StellaOps.ElkSharp/ElkEdgeRoutingScoring.BoundarySlots.cs

@@ -17,7 +17,9 @@ internal static partial class ElkEdgeRoutingScoring
     {
         var edgesById = edges.ToDictionary(edge => edge.Id, StringComparer.Ordinal);
         var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
-        var minClearance = ResolveMinLineClearance(nodes);
+        // Use node-size clearance for boundary-slot gaps: slot spacing depends
+        // on node face geometry, not inter-node spacing.
+        var minClearance = ResolveNodeSizeClearance(nodes);
         var coordinateTolerance = Math.Max(1d, Math.Min(6d, minClearance * 0.2d));
         var entries = new List<(string EdgeId, ElkPositionedNode Node, string Side, double Coordinate, bool IsOutgoing)>();
 

src/__Libraries/StellaOps.ElkSharp/ElkEdgeRoutingScoring.TargetJoin.cs

@@ -15,7 +15,9 @@ internal static partial class ElkEdgeRoutingScoring
         Dictionary<string, int>? severityByEdgeId,
         int severityWeight = 1)
     {
-        var minClearance = ResolveMinLineClearance(nodes);
+        // Use node-size clearance for target-join gaps: face slot spacing
+        // depends on node face geometry, not inter-node spacing.
+        var minClearance = ResolveNodeSizeClearance(nodes);
         var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
         var count = 0;
 

src/__Libraries/StellaOps.ElkSharp/ElkEdgeRoutingScoring.cs

@@ -239,6 +239,16 @@ internal static partial class ElkEdgeRoutingScoring
             return overrideClearance;
         }
 
+        return ResolveNodeSizeClearance(nodes);
+    }
+
+    /// <summary>
+    /// Node-size-based clearance (independent of NodeSpacing). Used for
+    /// face-related detections (target-join, boundary-slot) where the gap
+    /// depends on node face geometry, not inter-node routing corridors.
+    /// </summary>
+    private static double ResolveNodeSizeClearance(IReadOnlyCollection<ElkPositionedNode> nodes)
+    {
         var serviceNodes = nodes.Where(n => n.Kind is not "Start" and not "End").ToArray();
         return serviceNodes.Length > 0
             ? Math.Min(serviceNodes.Average(n => n.Width), serviceNodes.Average(n => n.Height)) / 2d