feat: US-004 — App shell layout and sidebar navigation

- Add electron-store@8 for sidebar collapse state persistence via settings tRPC router
- Add @fontsource/geist for self-hosted Geist font (remove Google Fonts CDN)
- Add right-edge vertical 'keep scrolling for AI' label with chevron-down in all views
- Wire AppShell collapse toggle to settings.setSidebarCollapsed tRPC mutation
- Fix ESLint config with eslint-import-resolver-typescript to resolve @/* path aliases

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main/router/index.ts

@@ -1,5 +1,6 @@
 import { initTRPC } from '@trpc/server';
 import { z } from 'zod';
+import { getStore } from '../store';
 
 const t = initTRPC.create();
 
@@ -134,6 +135,16 @@ const notesRouter = router({
     .mutation(() => null),
 });
 
+const settingsRouter = router({
+  getSidebarCollapsed: publicProcedure.query(() => getStore().get('sidebarCollapsed')),
+  setSidebarCollapsed: publicProcedure
+    .input(z.object({ collapsed: z.boolean() }))
+    .mutation(({ input }) => {
+      getStore().set('sidebarCollapsed', input.collapsed);
+      return null;
+    }),
+});
+
 const aiRouter = router({
   chat: publicProcedure
     .input(z.object({
@@ -152,6 +163,7 @@ const aiRouter = router({
 
 export const appRouter = router({
   health: healthRouter,
+  settings: settingsRouter,
   clients: clientsRouter,
   projects: projectsRouter,
   tasks: tasksRouter,

src/main/store.ts

@@ -0,0 +1,18 @@
+import Store from 'electron-store';
+
+interface AppSettings {
+  sidebarCollapsed: boolean;
+}
+
+let _store: Store<AppSettings> | null = null;
+
+export function getStore(): Store<AppSettings> {
+  if (!_store) {
+    _store = new Store<AppSettings>({
+      defaults: {
+        sidebarCollapsed: false,
+      },
+    });
+  }
+  return _store;
+}