SSR: file-path rendering, no component registry

The worker receives a file path in the JSON message, dynamically
imports it, renders it. No registerComponent API, no app entry file,
no export maps. Django's template backend resolves the template name
to an absolute path against DIRS, same as every other template engine.

  render(request, 'components/Hello.tsx', {'name': 'World'})

Verified working: curl http://localhost:8000/hello/ returns
  <div id="mizan-root"><div>Hello, World!</div></div>

Changes:
- worker.tsx: receives file path, dynamic import with cache
- bridge.py: sends file path instead of component name
- backend.py: resolves template name against DIRS to absolute path
- Fix bridge.py:147 bug (referenced deleted 'component' variable)
- Example app: Hello.tsx component, /hello/ view, template config

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

examples/django-react-site/frontend/components/Hello.tsx

@@ -0,0 +1,3 @@
+export default function Hello({ name }: { name: string }) {
+    return <div>Hello, {name}!</div>
+}