feat(01-01): create Zustand store with 6 slices, IPC batcher, and unit tests

- Install zustand 5.x and immer 11.x dependencies
- Create 6 Zustand slices: navigation, company, selection, ui, communication, social
- Create combined store with devtools + immer middleware
- Create IPC event batcher with 50ms debounce window (schedule/flush/dispose)
- Create typed selector hooks for narrow state subscriptions
- Add 14 unit tests covering store initialization, slice behaviors, and batcher timing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/renderer/lib/ipc-batcher.ts

@@ -0,0 +1,30 @@
+type BatchCallback = () => void;
+
+export function createEventBatcher(callback: BatchCallback, windowMs = 50) {
+  let timer: ReturnType<typeof setTimeout> | null = null;
+
+  function schedule() {
+    if (timer !== null) return; // already scheduled -- coalesce
+    timer = setTimeout(() => {
+      timer = null;
+      callback();
+    }, windowMs);
+  }
+
+  function flush() {
+    if (timer !== null) {
+      clearTimeout(timer);
+      timer = null;
+      callback();
+    }
+  }
+
+  function dispose() {
+    if (timer !== null) {
+      clearTimeout(timer);
+      timer = null;
+    }
+  }
+
+  return { schedule, flush, dispose };
+}