feat(deploy): switch to Oracle MySQL, separate CI runner, docker-compose deploy

- Prisma schema: sqlite → mysql provider
- Migration SQL rewritten as MySQL DDL (utf8mb4, DATETIME(3), AUTO_INCREMENT)
- Add migration_lock.toml for mysql provider
- Dockerfile.backend: drop node:22/sqlite deps, use node:20-slim
- entrypoint.sh: replace SQLite first-run logic with prisma migrate deploy + db seed
- docker-compose.prod.yml: production compose for /opt/webapps/okr on web VPS
  - reads DB creds from /opt/webapps/webapp-mysql.env
  - reads app secrets from /opt/webapps/okr/.env.app (written by CI)
  - port 80 (frontend), no conflict with Gitea 3000/Vault 8200
- ci.yml deploy-okr: moves from ubuntu-latest (web VPS) to ci-runner (161.33.149.243)
  - builds images on CI runner VPS (no heavy build on web/Gitea VPS)
  - transfers images via docker save | gzip | ssh | docker load
  - deploys via SSH + docker compose up on web VPS
- scripts/setup-ci-runner.sh: one-time setup script for CI runner VPS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

AINative_OKR_CASAN5/backend/prisma/schema.prisma

@@ -3,7 +3,7 @@ generator client {
 }
 
 datasource db {
-  provider = "sqlite"
+  provider = "mysql"
   url      = env("DATABASE_URL")
 }