Migrate frontend to Vite + Hono CopilotKit runtime

Replaces the Next.js scaffold with a Vite SPA paired with a Hono
sidecar that hosts the CopilotKit runtime and proxies AG-UI traffic
to the MAF backend. Adds dev/prod Dockerfile, .dockerignore,
.gitignore, pnpm workspace config, and updates entrypoints
(main.tsx / App.tsx / index.css / index.html) plus the service
worker accordingly.

Server middleware reconciles MAF MESSAGES_SNAPSHOT id mismatches
so post-tool-call assistant text doesn't render twice, suppresses
duplicate text emitted alongside render tools, and strips OpenAI
training-token leaks from streamed deltas.

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

frontend/.gitignore

@@ -0,0 +1,41 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/versions
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# env files (can opt-in for committing if needed)
+.env*
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts