Bundle Bootstrap via Vite instead of jsDelivr CDN

[zachcasper]

Summary

Bundle Bootstrap through the Vite build instead of loading it from the jsDelivr CDN, so the Todo list demo renders with correct styling even when an organization's Microsoft Defender policy blocks npm-backed CDN URLs.

Reason for change

client/index.html referenced Bootstrap CSS and JS from cdn.jsdelivr.net. In environments where Microsoft Defender blocks npm-backed jsDelivr URLs, the browser fails to load these resources (ERR_SOCKET_NOT_CONNECTED), so the demo loads without Bootstrap styling. Installing Bootstrap as a client dependency and importing it into the Vite bundle removes the runtime dependency on an external CDN.

Fixes #2638

How to test

1. Build the demo image (pass an approved npm registry if the default is blocked):

   docker build --build-arg NPM_CONFIG_REGISTRY="$(npm config get registry)" -t ghcr.io/radius-project/samples/demo:test ./samples/demo

2. Load it into a local Kind cluster and deploy:

   kind load docker-image ghcr.io/radius-project/samples/demo:test --name <cluster>

3. Edit the container image in the app.bicep to point to :test rather than :latest

4. Deploy

   rad deploy ./samples/demo/app.bicep --application demo --environment default

5. Port-forward the demo container and open it in a browser.

6. Confirm the UI renders with Bootstrap styling and the served HTML contains no cdn.jsdelivr.net references.

File change summary

File	Summary of change
samples/demo/client/src/index.tsx	Import Bootstrap CSS and JS from the bundle; remove duplicate index.css import
samples/demo/client/index.html	Remove jsDelivr Bootstrap CSS and JS references
samples/demo/client/public/index.html	Remove jsDelivr Bootstrap CSS and JS references
samples/demo/client/package.json	Add bootstrap as a client dependency
samples/demo/client/package-lock.json	Lockfile entry for bootstrap
samples/demo/package.json	Remove unused server-side bootstrap dependency
samples/demo/package-lock.json	Remove server-side bootstrap lockfile entry
samples/demo/Dockerfile	Add NPM_CONFIG_REGISTRY build arg so the image can build through an approved npm registry proxy