Release 4.0.0-rc1 — ProxySQL LLC maintainership announcement

[renecannao]

Phase 1, Task 7

Part of: Phase 1 — Identity & Trust (4.0.0-rc1)
Plan: docs/superpowers/plans/2026-03-23-phase1-identity-and-trust.md
Depends on: All Phase 1 issues (#1-#6) merged and CI green

Description

Bump version to 4.0.0-rc1 and create a GitHub Release announcing ProxySQL LLC as the new maintainer.

Changes

• Update RELEASE_VERSION from 3.2.6 to 4.0.0-rc1
• Create annotated git tag v4.0.0-rc1
• Create GitHub Release (marked as pre-release) with notes covering:
  • ProxySQL LLC is the new maintainer
  • Brief history and motivation
  • What changed in this release
  • What's coming in 4.0.0 (Go module path migration, dependency updates, code quality)
  • How to contribute (link to CONTRIBUTING.md)

Acceptance Criteria

• RELEASE_VERSION contains 4.0.0-rc1
• Tag v4.0.0-rc1 exists
• GitHub Release exists and is marked as pre-release
• Release notes clearly communicate the maintainership change

[renecannao]

Done in PR #16 — v4.0.0-rc1 tagged