Restructure repo into five-package AFI architecture

Mizan is an Application Framework Interface (AFI) with five
independent packages:

  packages/
    mizan-ast/       Language layer (source → KDL schema)
    mizan-schema/    IR layer (KDL schema definition)
    mizan-rpc/       Protocol layer (client gen + server adapters)
      adapters/django/   ← was django/
      generator/         ← was react/src/generator/
    mizan-csr/       State layer (client state engine)
      adapters/react/    ← was react/
    mizan-ssr/       Rendering layer (server-side rendering)

Each package is independent. The adapter directories contain the
framework-specific implementations. Stub packages (ast, schema, ssr)
establish the structure for future work.

264 Django tests + 33 React tests pass from new locations.

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

examples/django-react-site/harness/django.config.mjs

@@ -10,9 +10,9 @@ export default {
     source: {
         django: {
             managePath: path.join(root, 'examples/django-react-site/backend/manage.py'),
-            command: [path.join(root, 'django/.venv/bin/python')],
+            command: [path.join(root, 'packages/mizan-rpc/adapters/django/.venv/bin/python')],
             env: {
-                PYTHONPATH: `${path.join(root, 'django/src')}:${path.join(root, 'examples/django-react-site/backend')}`,
+                PYTHONPATH: `${path.join(root, 'packages/mizan-rpc/adapters/django/src')}:${path.join(root, 'examples/django-react-site/backend')}`,
                 DJANGO_SETTINGS_MODULE: 'testapp.settings',
             },
         },