chore: move widget source into sidecar repo (widget-src/)

Widget builds from widget-src/ → public/widget.js
Vite outDir updated to ../public
.gitignore excludes node_modules

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

widget-src/src/main.tsx

@@ -0,0 +1,40 @@
+import { render } from 'preact';
+import { initApi, fetchInit } from './api';
+import { Widget } from './widget';
+import type { WidgetConfig } from './types';
+
+const init = async () => {
+    const script = document.querySelector('script[data-key]') as HTMLScriptElement | null;
+    if (!script) { console.error('[HelixWidget] Missing data-key attribute'); return; }
+
+    const key = script.getAttribute('data-key') ?? '';
+    const baseUrl = script.src.replace(/\/widget\.js.*$/, '');
+
+    initApi(baseUrl, key);
+
+    let config: WidgetConfig;
+    try {
+        config = await fetchInit();
+    } catch (err) {
+        console.error('[HelixWidget] Init failed:', err);
+        return;
+    }
+
+    // Create shadow DOM host
+    const host = document.createElement('div');
+    host.id = 'helix-widget-host';
+    host.style.cssText = 'position:fixed;bottom:20px;right:20px;z-index:999999;font-family:-apple-system,sans-serif;';
+    document.body.appendChild(host);
+
+    const shadow = host.attachShadow({ mode: 'open' });
+    const mountPoint = document.createElement('div');
+    shadow.appendChild(mountPoint);
+
+    render(<Widget config={config} shadow={shadow} />, mountPoint);
+};
+
+if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', init);
+} else {
+    init();
+}