Two compilers that walk a graph the same way walk it through one emitter (#85)

Refactoring round two: the particle and shader compilers share emitGraph.ts (cycle detection,
duplicate names, emit order) and keep only their rules. FontLibrary and TextureLibrary sit on
FileLibrary (base URL, loading/failed bookkeeping, listeners); SoundLibrary keeps its own
contract. The three Create*Command share ImportFileCommand, the three renames share
RenameCommand - class names stay. bandBounds() in framing.ts and portNameField() in
portSection.ts replace in-file clones, and three comments that told history now state the rule.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/editor/inspector/portSection.ts

@@ -175,12 +175,7 @@ function buildPickedPortSection(
   for (const port of ports) {
     const toggle = writeToggle(host, assetId, node, port);
     if (custom) {
-      const name = new TextField(port.key, {
-        width: NAME_WIDTH,
-        onChange: (next) =>
-          host.state.execute(new RenamePortCommand(assetId, node.id, port.key, next.trim())),
-      });
-      portRow(host, assetId, node, port, name, toggle);
+      portRow(host, assetId, node, port, portNameField(host, assetId, node, port), toggle);
       continue;
     }
     const def = choices.find((d) => d.key === port.key);
@@ -236,13 +231,14 @@ export function buildPortSection(
           : 'No outputs yet. Every output added here becomes a result of running this behavior.',
     );
 
-  for (const port of ports) {
-    const name = new TextField(port.key, {
-      width: NAME_WIDTH,
-      onChange: (next) => host.state.execute(new RenamePortCommand(assetId, node.id, port.key, next.trim())),
-    });
-    portRow(host, assetId, node, port, name);
-  }
+  for (const port of ports) portRow(host, assetId, node, port, portNameField(host, assetId, node, port));
+}
+
+function portNameField(host: InspectorHost, assetId: string, node: GraphNode, port: DeclaredPort): TextField {
+  return new TextField(port.key, {
+    width: NAME_WIDTH,
+    onChange: (next) => host.state.execute(new RenamePortCommand(assetId, node.id, port.key, next.trim())),
+  });
 }
 
 function writeToggle(host: InspectorHost, assetId: string, node: GraphNode, port: DeclaredPort): Widget[] {