feat(mcp): finalize scaffolding and factory entry

Adds packages/mcp/.gitignore, src/index.ts (public API barrel),
src/server.ts (createPascalMcpServer factory), and a smoke test
for the public API.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/mcp/src/index.ts

@@ -0,0 +1,4 @@
+export { SceneBridge } from './bridge/scene-bridge'
+export { type CreatePascalMcpServerOptions, createPascalMcpServer } from './server'
+
+export const version = '0.1.0'