Upgrade Go to v1.27.0

fix: security & reliability hardening for rate limiter, auth, and audit

doc: update Readme

feat: add observability stack (Grafana, Loki, Promtail)

perf(db): replace redundant indexes with composite index for licenses

fix: remove docker job from CI

fix: change branch name for CI

feat: CI

feat: add custom params (JSONB) to licenses

Update: README.md

Update: README.md

Create: CONTRIBUTING

Create: CODE_OF_CONDUCT

Create: SECURITY