A transition carries a name, so a state needs no visible port (#52)

A state keeps its `in`/`out` exec pins in the model and the editor never draws
them. That is the whole trick: connecting, undo, deleting a state and saving all
keep working untouched, because `normalizeGraph` filters nodes and never edges,
and no edge ever checks its port key against a NodeDef. Only two places change --
`NodeView.redraw` stops drawing the row, and `portAt` refuses to hand one out, so
an invisible pin cannot be grabbed either.

Transitions are drawn by right-clicking a state, `Make transition`, then clicking
the target. The armed mode takes the same shape as a live drag, so the existing
preview draws it with no second code path, and it dies with Escape, a click on
empty canvas or a switch to another asset.

Removing the pins removed the only handle a transition had: edges have no
hit-test anywhere, and the pin right-click was the sole route to Disconnect.
The inspector's TRANSITIONS OUT / TRANSITIONS IN lists are therefore not a
convenience, they are the delete path.

`GraphEdge` gained an optional `label`, which `normalizeGraph` has to pass
through explicitly or a saved name is dropped on load. `State transition`
replaces `Next state`: it takes the machine on an input port and the name from a
picker, and resolves against the *current* state. Names are deliberately not
unique across a machine -- two states may both have an `alarm` -- so a node named
`alarm` moves whichever state has one, and an empty name follows the single
unnamed edge.

The geometry moved to a Pixi-free `transitions.ts`: a gap to the box border, and
a fan that puts a pair of opposite edges beside each other instead of on top of
each other. Keeping it as plain maths is what let a screenshot bug become a unit
test -- an earlier pin-to-pin line ran under the target node and took its
arrowhead with it, because `nodeLayer` sits above `edgeLayer`.

One limit stands and is not fixed here: `ConnectCommand` rejects a second edge
between the same two states ("Already connected"), because every transition
hangs off the same two ports. With names, `A --alarm--> B` beside
`A --seen--> B` is a sensible pair, so this is worth its own issue.

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

src/core/graph/GraphInterpreter.ts

@@ -105,7 +105,7 @@ export class GraphInterpreter {
     const def = this.def(node);
     if (!def?.run) return;
     const inputs = this.collectInputs(node, ctx);
-    const result = def.run(ctx, inputs, node.params, def, entry);
+    const result = def.run(ctx, inputs, node.params, def, entry, this.lookup);
     const returned = result.call ? this.call(result.call, ctx, depth) : {};
     const produced = { ...result.outputs, ...returned };
     if (!def.read) this.frame.outputCache.set(node.id, produced);
@@ -197,7 +197,8 @@ export class GraphInterpreter {
       throw new Error('Behavior graph exceeded the step limit (data cycle?)');
     // Mark before evaluating so a data cycle reads null instead of recursing forever.
     this.frame.dataCache.set(nodeId, {});
-    const outputs = def.run(ctx, this.collectInputs(source, ctx), source.params, def, '').outputs ?? {};
+    const outputs =
+      def.run(ctx, this.collectInputs(source, ctx), source.params, def, '', this.lookup).outputs ?? {};
     this.frame.dataCache.set(nodeId, outputs);
     this.trace?.onNode(nodeId);
     this.record(nodeId, outputs);