feat(site-builder): capture recent console errors for issue reports

Ring buffer of the most recent console.error/window-error messages
(20 max, 500 chars each, message text only) for Task 19's report
payload. installConsoleErrorBuffer() is idempotent via a marker
stamped on the patched console.error itself (not just a module-scoped
flag), so React 18 StrictMode double-invocation or HMR re-running this
module's top level can't wrap an already-patched console.error and
build a growing chain. The patch always chains to the original.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

craft/src/main.tsx

@@ -2,8 +2,13 @@ import React from 'react';
 import ReactDOM from 'react-dom/client';
 import { App } from './App';
 import { WhpConfig } from './types';
+import { installConsoleErrorBuffer } from './utils/console-buffer';
 import './styles/editor.css';
 
+// Installed before React mounts so errors thrown during the first render are
+// captured too.
+installConsoleErrorBuffer();
+
 // Read WHP_CONFIG injected by PHP wrapper (or null for standalone dev)
 const whpConfig: WhpConfig | null = (window as any).WHP_CONFIG || null;