feat(control): grid snap, NPC context actions, and overlay dim fix

Re-enable users-branch UI, snap session tokens to square/hex grid from the control preview, refine inactive/open-info NPC menus, block marker actions while an effect brush is active, and dim materials/NPC overlays only when they are open.

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

app/main/tokens/tokenGridSnapSessionStore.ts

@@ -0,0 +1,21 @@
+export type TokenGridSnapSessionState = {
+  enabled: boolean;
+};
+
+export class TokenGridSnapSessionStore {
+  private enabled = false;
+
+  getState(): TokenGridSnapSessionState {
+    return { enabled: this.enabled };
+  }
+
+  setEnabled(enabled: boolean): TokenGridSnapSessionState {
+    this.enabled = Boolean(enabled);
+    return this.getState();
+  }
+
+  reset(): TokenGridSnapSessionState {
+    this.enabled = false;
+    return this.getState();
+  }
+}