feat(npcs): inspect cards, Show overlay, and optional external link

Clicking an NPC tile opens description cards (multi-select accordion); Show puts avatars on screen. Optional URL opens a webview tab. Avatar pan in the editor commits on pointer up.

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

app/main/npcs/npcsOverlayStore.test.ts

@@ -0,0 +1,40 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { asNpcId } from '../../shared/types/ids';
+
+import { NpcsOverlayStore } from './npcsOverlayStore';
+
+const a = asNpcId('npc_a');
+const b = asNpcId('npc_b');
+
+void test('NpcsOverlayStore: inspect is independent from overlay show', () => {
+  const store = new NpcsOverlayStore();
+  store.dispatch({ kind: 'inspect.toggle', npcId: a });
+  store.dispatch({ kind: 'inspect.show', npcId: b });
+  assert.deepEqual(store.getState().inspectNpcIds, [a, b]);
+  assert.equal(store.getState().inspectFocusNpcId, b);
+  assert.deepEqual(store.getState().activeNpcIds, []);
+
+  store.dispatch({ kind: 'show', npcId: a });
+  assert.deepEqual(store.getState().activeNpcIds, [a]);
+  assert.deepEqual(store.getState().inspectNpcIds, [a, b]);
+
+  store.dispatch({ kind: 'hide' });
+  assert.deepEqual(store.getState().activeNpcIds, []);
+  assert.deepEqual(store.getState().inspectNpcIds, [a, b]);
+
+  store.dispatch({ kind: 'inspect.toggle', npcId: a });
+  assert.deepEqual(store.getState().inspectNpcIds, [b]);
+});
+
+void test('NpcsOverlayStore: clear wipes inspect; ensureNpcStillExists prunes', () => {
+  const store = new NpcsOverlayStore();
+  store.dispatch({ kind: 'inspect.show', npcId: a });
+  store.dispatch({ kind: 'show', npcId: b });
+  store.ensureNpcStillExists(new Set([a]));
+  assert.deepEqual(store.getState().inspectNpcIds, [a]);
+  assert.deepEqual(store.getState().activeNpcIds, []);
+  store.clear();
+  assert.deepEqual(store.getState().inspectNpcIds, []);
+});