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.test.ts

@@ -0,0 +1,12 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { TokenGridSnapSessionStore } from './tokenGridSnapSessionStore';
+
+void test('TokenGridSnapSessionStore: set and reset', () => {
+  const store = new TokenGridSnapSessionStore();
+  assert.equal(store.getState().enabled, false);
+  assert.equal(store.setEnabled(true).enabled, true);
+  assert.equal(store.getState().enabled, true);
+  assert.equal(store.reset().enabled, false);
+});