fix: use Strapi v4 official 'schema: strapi' option instead of searchPath/options workarounds

fix: set search_path=strapi at pg connection level to isolate from Supabase public schema

fix: use strapi schema to isolate from Supabase public schema (config/database.js)

fix: set searchPath to strapi schema to avoid Supabase wrappers extension conflict

feat: config/database.js

feat: Complete Strapi 4 app structure with Postgres config

feat: Initial Strapi CMS setup with Supabase PostgreSQL