feat(examples): add nextjs-prisma full-stack reference package

[PinoyQ8]

Summary

Adds a full-stack Next.js and Prisma reference architecture under examples/nextjs-prisma-solohost/. This package provides developers and node operators with an authoritative-compliant pattern for:

• Server-rendered Next.js Web3 applications running within Docker.
• Decoupled persistent database access via host.docker.internal:host-gateway.
• Dynamic environment variable injection defined through config_options.yml.

Validation Gate

Passed the authoritative hosted validator with zero failures:

python3 scripts/validate_api.py examples/nextjs-prisma-solohost
[OK]   examples/nextjs-prisma-solohost
Result: OK — passes the authoritative validator; ready to paste into SoloHost.