fix: make the web workspace deployable on Vercel

[aryamthecodebreaker]

Summary

• build only the @fixmap/web workspace on Vercel
• point Vercel at the actual nested Next.js output in apps/web/.next
• replace the last public “review receipt” metadata claims with truthful diagnostics copy
• add canonical, robots, Open Graph, and Twitter metadata for the production site

Why

The fixmap Vercel project is rooted at the repository root. Its existing production deployment is three days old, and a deployment of current main built successfully but failed because Vercel looked for .next/routes-manifest.json at the root while Next wrote it to apps/web/.next. The production alias did not move.

This tracked configuration makes root deployments deterministic without relying on hidden dashboard root-directory state.

Verification

• web workspace typecheck passed
• web workspace ESLint passed
• vercel.json parses and selects npm run build:web + apps/web/.next
• Vercel preview deployment built from a clean worktree with npm ci (0 vulnerabilities), Next.js 16.2.10, TypeScript, and all static routes green
• authenticated preview checks confirmed:
  • public GitHub repository command present
  • “Explain the route” present
  • old “Leave a receipt” heading absent
  • truthful explainable diagnostics metadata present
  • canonical and index/follow robots metadata present

Preview: https://fixmap-luj5pp9j9-aryam-goyals-projects.vercel.app