revert: restore the-epic-stack demo to workspace integration

- Remove workspace exclusion from pnpm-workspace.yaml
- Update lingo.dev dependency to use workspace:* reference

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: davidturnbull

demo/the-epic-stack/.npmrc

@@ -1,2 +1,3 @@
 legacy-peer-deps=true
 registry=https://registry.npmjs.org/
+shared-workspace-lockfile=false

demo/the-epic-stack/package.json

@@ -88,7 +88,7 @@
     "input-otp": "^1.4.2",
     "intl-parse-accept-language": "^1.0.0",
     "isbot": "^5.1.27",
-    "lingo.dev": "^0.108.0",
+    "lingo.dev": "workspace:*",
     "litefs-js": "^2.0.2",
     "lru-cache": "^11.1.0",
     "mime-types": "^3.0.1",