docs: correct README (Gemini in prod, manual Vercel deploy)

[vedantggwp]

Two factual corrections flagged during the live-status review: production LLM is Gemini via LLM_PROVIDER (README said Anthropic); GitHub auto-deploy is not wired, so deploys are manual via vercel --prod (README said auto-deploy).

[devin-ai-integration]

Code Review — PR #3

Overall: Correct and minimal. Two factual fixes to the README — both accurate.

Findings

1. Stale reference remains: scan.neuroedge.co.uk — The README still says the scan-service runs behind Caddy at scan.neuroedge.co.uk → localhost:3001 after this PR. Since the neuroedge.co.uk domain doesn't resolve (and PR feat: free open-source demo — remove paid subsystem #4 later confirmed "it never existed"), this is misleading. The actual path is Caddy on :80 → localhost:3001, reached via the VPS IP 65.21.185.228 (documented in ENGINE.md). This PR was a good opportunity to fix this reference too.

2. "Stripe" still in the tech stack — After this PR (but before PR feat: free open-source demo — remove paid subsystem #4), the tech stack line still lists Stripe in the frontend stack. This is correct at the time of this PR (Stripe hadn't been removed yet), but worth noting the sequencing.

3. The Deployment Protection note was removed — The old text mentioned "bare deployment-specific *.vercel.app URLs are auth-walled by Vercel Deployment Protection." The new text drops this. If Deployment Protection is still enabled on Vercel, this is useful context that was lost. If it was disabled, the removal is fine.

No bugs — clean docs fix.