Replace legacy demos with the 200ms demo

[youssefea]

Summary

• remove the legacy base-account/, mini-apps/, and base-app-coins/ trees
• remove apps/demo_notif_app/
• add 200ms-demo/ as a standalone top-level Vite + React demo
• add a build-only validation workflow for the demo
• update the repository README to reflect the remaining demos

200ms demo

The page generates and funds a Vibenet EIP-8130 account without a wallet connection, then streams USDV through real nonce-free onchain transfers at approximately five transactions per second. It includes exact rational rate accumulation, confirmation-anchored counter motion, receipt/phase reconciliation, exact-raw rebroadcast, backpressure, automatic ETH/USDV top-ups, reset recovery, and explorer-linked transactions.

Live preview

• https://youssefea.github.io/demos/200ms/

The preview is deployed only from the personal youssefea/demos fork. This PR does not configure or deploy base.github.io/demos.

Live verification

• 50-transfer gate: 5.04 accepted tx/s, all transfers confirmed
• five-minute soak: 1,500 transfers, 5.00 accepted tx/s, 4.95 confirmed tx/s
• one automatic ETH top-up
• two missing submissions recovered by exact signed-byte rebroadcast

Checks

• npm ci
• npm run test:math
• npm run build
• npm run build:pages
• hosted build emits /demos/200ms/-prefixed assets
• CodeQL
• git diff --check

Notes

• USDV is Vibenet test currency, not USDC.
• Browser keys are devnet-only bearer material stored in localStorage.
• The vendored AA bundle is pinned and documented in vendor/aa/SOURCE.md.
• The Vite build warns about the expected ~591 KB application chunk because the AA bundle is self-contained.

[youssefea]

Deployment update:

• all PR checks are green, including CodeQL and the Pages build
• the workflow deployed successfully from a preview fork
• live demo: https://youssefea.github.io/demos/
• enabling Pages on base/demos still requires an admin; the API returned 404 with write-only repository access

After Pages is enabled with Source: GitHub Actions, merging this PR will deploy the same artifact to the official organization URL.

[youssefea]

Naming and deployment update:

• renamed the top-level demo to 200ms-vibenet/
• renamed the product to 200ms Vibenet
• changed the hosted base path to /demos/200ms/
• replaced the Pages deployment workflow in base/demos with a build-only validation workflow
• there is no deployment to base.github.io/demos
• the live deployment is maintained only in the personal preview fork at https://youssefea.github.io/demos/200ms/

[youssefea]

Final deployment verification:

• live: https://youssefea.github.io/demos/200ms/
• https://youssefea.github.io/demos/200ms redirects to the trailing-slash path
• the HTML, JavaScript, CSS, and Base logo return HTTP 200
• the fork root now returns 404, so the demo is hosted only under /200ms/
• base/demos has no Pages site enabled and the PR workflow has only contents: read; it performs validation only and cannot deploy to base.github.io/demos
• all PR checks are green

[youssefea]

Final naming update:

• demo name is now 200ms demo
• top-level directory is now 200ms-demo/
• removed the Base logo from the top-left header and replaced it with the text 200ms demo
• the live URL remains https://youssefea.github.io/demos/200ms/
• the PR remains build-only and does not deploy to base.github.io/demos