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/model/Asset.ts

@@ -83,8 +83,8 @@ export interface AnimationAsset extends AssetBase {
 }
 
 /**
- * The graph holds one `State` node per state and nothing else; a behavior reads the machine's
- * current state through `State branch` and moves it through `Set state`.
+ * The graph holds one `State` node per state and an edge per transition; a behavior reads the
+ * machine's current state through `State branch` and moves it through `Set state` or `State transition`.
  */
 export interface StateMachineAsset extends AssetBase {
   type: 'statemachine';

src/core/model/graphLookup.ts

@@ -1,5 +1,5 @@
 import type { GraphLookup } from '../graph/lookup';
-import { statesOf } from '../graph/stateMachine';
+import { statesOf, transitionsOf } from '../graph/stateMachine';
 import { resolveAssetProps } from '../properties/resolve';
 import { findAssetOf, type Project } from './Project';
 
@@ -16,7 +16,12 @@ export function graphLookup(project: Project): GraphLookup {
     },
     machine: (assetId) => {
       const asset = findAssetOf(project, assetId, 'statemachine');
-      return asset ? { name: asset.name, states: statesOf(asset.graph) } : null;
+      if (!asset) return null;
+      return {
+        name: asset.name,
+        states: statesOf(asset.graph),
+        transitions: transitionsOf(asset.graph),
+      };
     },
   };
 }