feat: add unit tests, Docker polish, and workbench UX improvements

Unit tests: Consumer class (7), recursive-splitter (10), parseJsonResponse (11) — 28 total.
Docker: add 5 commented LLM provider services, dev compose override, .env.example.
Workbench: chat persistence, error boundary, disconnect banner, prompts error handling.

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

ts/packages/flow/vitest.config.ts

@@ -0,0 +1,6 @@
+import { defineConfig } from "vitest/config";
+export default defineConfig({
+  test: {
+    globals: true,
+  },
+});