Edit a Filter in its node and resize EQ and Filter nodes (#385)

A Filter sounds like one band of the Parametric EQ, but it keeps what
the EQ cannot: linked numbers, the all-pass and +-40 dB. So it stays a
node of its own and gets the EQ's editor with itself as the one band.
The editors also stop running out of their room: what does not fit is
left out instead of being cut.

- The curve of the EQ is now BandCurve with a host the EQ and the
  Filter both fill. CurvePanel holds what their panels share.
- FilterPanel shows the Filter as one band. A drag of its handle sets
  frequency and gain as one undo step. A number fed by a link is
  greyed out and the drag leaves it alone.
- A double-click on the Filter's title opens the same in a tab of its
  own. Delete there does nothing, the node stays.
- The Filter is tapped like the EQ, so its node and its tab draw the
  spectrum of what passes it. A tap is two gain nodes per voice, the
  analysers are made only while someone listens.
- EqFace and FilterFace are one CurveFace now, given the panel.
- EQ and Filter nodes have a corner to resize them, drawn like the
  floating window's. The size is saved on the node as `size`, each
  drag is one undo step, the least is 240 x 120.
- In the node the help line is gone. The row of numbers comes in only
  once the curve keeps 120 px of height. A group of the row that does
  not fit is not drawn, the one on the right first.
- A frequency or dB label that would run into the one before it is
  left out.
- The all-pass is drawn flat. The curve's maths takes every shape a
  Filter has.

Found on the way:
- The instrument presets set nodes 240 apart. A Filter with its
  editor is about 700 wide and covered the Bitcrusher, so a Filter
  now takes four columns.

Tests:
- Unit: 8 new (filter band, resize command and save, fitting rules),
  stage lists with a Filter now hold its taps
- e2e 34 (atx): ALL PASSED, 130 checks (4 new)
- Gate (atx): CHECK EXIT 0, 284 files, 4367 tests

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/editor/graph/GraphCanvas.ts

@@ -371,7 +371,11 @@ export class GraphCanvas extends Widget {
     const asset = this.asset();
     if (!asset) return;
     this.annotationLayer.sync(asset.graph);
-    for (const node of asset.graph.nodes) this.views.get(node.id)?.position.set(node.x, node.y);
+    for (const node of asset.graph.nodes) {
+      const view = this.views.get(node.id);
+      view?.position.set(node.x, node.y);
+      view?.refit();
+    }
     this.redraw();
   }
 
@@ -539,14 +543,17 @@ export class GraphCanvas extends Widget {
     return this.views.get(nodeId)?.face ?? null;
   }
 
-  /** A node's box on screen and the keys of its ports, for the check scripts. */
-  nodeScreen(nodeId: string): { rect: Rect; inputs: string[]; outputs: string[] } | null {
+  /** A node's box on screen, the keys of its ports and the corner it is resized by (#385), for the check scripts. */
+  nodeScreen(
+    nodeId: string,
+  ): { rect: Rect; inputs: string[]; outputs: string[]; corner: { x: number; y: number } | null } | null {
     const view = this.views.get(nodeId);
     if (!view) return null;
     return {
       rect: globalRect(view, view.w, view.h),
       inputs: view.def.inputs.map((p) => p.key),
       outputs: view.def.outputs.map((p) => p.key),
+      corner: view.cornerGlobal(),
     };
   }
 
@@ -697,6 +704,12 @@ export class GraphCanvas extends Widget {
       this.wiring.startDrag({ nodeId: view.node.id, port: hit.port.key, isOutput: hit.isOutput }, e.global);
       return;
     }
+    if (view.cornerAt(local.x, local.y)) {
+      this.state.select(nodeSelection(this.assetId, [view.node.id]));
+      this.nodeLayer.addChild(view); // raise
+      this.drags.grabCorner(view, e.global);
+      return;
+    }
     // Like the hierarchy's chevron: it folds, and leaves the selection alone.
     if (view.chevronAt(local.x, local.y)) {
       this.state.execute(new CollapseNodesCommand(this.assetId, [view.node.id], !view.collapsed));
@@ -843,7 +856,7 @@ export class GraphCanvas extends Widget {
       return;
     }
     this.panning = null;
-    if (this.drags.releaseBox()) {
+    if (this.drags.releaseCorner() || this.drags.releaseBox()) {
       this.redraw();
       return;
     }