feat(players): app Players library and circular NPC tokens on scenes

Add userData players/teams, scene npcTokens with hex-inscribed sizing, session scale synced to presentation, and Playwright e2e coverage.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/main/players/sceneNpcTokensSessionStore.ts

@@ -0,0 +1,73 @@
+import {
+  clampNpcTokenSessionScale,
+  DEFAULT_NPC_TOKEN_SESSION_SCALE,
+  type SceneNpcTokensSessionEvent,
+  type SceneNpcTokensSessionState,
+} from '../../shared/types/appPlayers';
+
+function emptyState(revision = 1): SceneNpcTokensSessionState {
+  return {
+    revision,
+    byPlacementId: {},
+    scale: DEFAULT_NPC_TOKEN_SESSION_SCALE,
+  };
+}
+
+export class SceneNpcTokensSessionStore {
+  private state: SceneNpcTokensSessionState = emptyState();
+
+  getState(): SceneNpcTokensSessionState {
+    return this.state;
+  }
+
+  reset(): SceneNpcTokensSessionState {
+    if (
+      Object.keys(this.state.byPlacementId).length === 0 &&
+      this.state.scale === DEFAULT_NPC_TOKEN_SESSION_SCALE
+    ) {
+      return this.state;
+    }
+    this.state = emptyState(this.state.revision + 1);
+    return this.state;
+  }
+
+  dispatch(event: SceneNpcTokensSessionEvent): SceneNpcTokensSessionState {
+    switch (event.kind) {
+      case 'clear':
+        return this.reset();
+      case 'setScale': {
+        const scale = clampNpcTokenSessionScale(event.scale);
+        if (this.state.scale === scale) return this.state;
+        this.state = {
+          ...this.state,
+          revision: this.state.revision + 1,
+          scale,
+        };
+        return this.state;
+      }
+      case 'move': {
+        const placementId = String(event.placementId ?? '');
+        if (!placementId) return this.state;
+        const nx = Math.max(0, Math.min(1, event.nx));
+        const ny = Math.max(0, Math.min(1, event.ny));
+        if (!Number.isFinite(nx) || !Number.isFinite(ny)) return this.state;
+        const prev = this.state.byPlacementId[placementId];
+        if (prev && prev.nx === nx && prev.ny === ny) return this.state;
+        this.state = {
+          revision: this.state.revision + 1,
+          byPlacementId: {
+            ...this.state.byPlacementId,
+            [placementId]: { nx, ny },
+          },
+          scale: this.state.scale,
+        };
+        return this.state;
+      }
+      default: {
+        const _exhaustive: never = event;
+        void _exhaustive;
+        return this.state;
+      }
+    }
+  }
+}