Implement M1 authoring loop: library, editor, live preview, persistence

M1 MVP from docs/IMPLEMENTATION-PLAN.md, with the /alignment pass applied.

- core: Snippet model + factory; prepareSpecForRender (copy-not-mutate); per-theme Vega chart config
- state/orchestration: SnippetStore with debounced auto-save; IndexedDB adapter + read-time migration; startup hydration + write-through persistence
- ui: SnippetLibrary, SpecEditor (Monaco edcore.main — full editor features, JSON-only languages), LivePreview
- build: Monaco/Vega manual chunks; raised PWA precache ceiling
- alignment: flush a valid draft on snippet switch (+regression tests); TODO breadcrumbs for the preview render race and the window.confirm delete
- housekeeping: gitignore .claude/projects/

src/main.tsx

@@ -1,5 +1,6 @@
 import { createRoot } from 'react-dom/client';
 import { App } from './app/App';
+import { initApp } from './app/orchestration/startup';
 import { useAppStore } from './app/stores/AppStore';
 import '../styles/base.css';
 
@@ -13,4 +14,9 @@ useAppStore.subscribe((state, prev) => {
   if (state.uiTheme !== prev.uiTheme) applyTheme(state.uiTheme);
 });
 
+// Load the library from IndexedDB (seeding a sample on first run) and wire
+// persistence. Fire-and-forget: the UI renders immediately and fills in when
+// hydration resolves.
+void initApp();
+
 createRoot(document.getElementById('app')!).render(<App />);