Replace remote Tailwind CSS with a local minimal subset; refine .gitignore and dist structure.

- Added a minimal `tailwind.min.css` with utilities tailored to app needs (`app/web/dist/`).
- Updated `.gitignore` to include specific `dist/` paths while maintaining clean build artifacts.
- Added local `dist` files (`index.css`, `index.js`) for better control over UI styling and build outputs.

.gitignore

@@ -94,7 +94,10 @@ cmd/benchmark/data
 !.dockerignore
 !*.jsx
 !*.tsx
-!/dist
+!app/web/dist
+!/app/web/dist
+!/app/web/dist/*
+!/app/web/dist/**
 !bun.lock
 # ...even if they are in subdirectories
 !*/