Edit the graph during play and watch values and flow run through it

The graph was only locked by five edit-mode guards in GraphCanvas. The
running game reads the graph by reference each frame, so a new node, edge,
changed value, disconnect or undo takes effect from the next frame. Stop
discards these edits like everything else changed in play. A new On start
node does not fire for a behavior that has already started.

During play every data output shows the value it last produced, in the
highlight colour and refreshed ten times a second. Values are kept per
graph, because node ids are only unique within one; with several
instances the most recent value wins. The Variables node reads the live
variable bag, so only its own outputs are kept, as a snapshot.

Each time an exec edge fires, a bead runs along it in 0.3 s, at most one
every 0.15 s per edge, following the same curve the edge is drawn with.
Beads run on game time and freeze while paused; the game logic is
unchanged.

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

src/ui/Theme.ts

@@ -77,6 +77,7 @@ export type TextStyleToken =
   | 'override'
   | 'small'
   | 'warning'
+  | 'live'
   | 'title'
   | 'mono'
   | 'accent'
@@ -107,6 +108,9 @@ export function textStyle(token: TextStyleToken = 'body'): TextStyle {
     case 'warning':
       style = new TextStyle({ ...base, fontSize: Theme.smallFontSize, fill: Theme.colors.danger });
       break;
+    case 'live':
+      style = new TextStyle({ ...base, fontSize: Theme.smallFontSize, fill: Theme.colors.hot });
+      break;
     case 'title':
       style = new TextStyle({
         ...base,