Rebrand README for ProxySQL LLC maintainership

[renecannao]

Phase 1, Task 1

Part of: Phase 1 — Identity & Trust (4.0.0-rc1)
Plan: docs/superpowers/plans/2026-03-23-phase1-identity-and-trust.md

Description

Rewrite README.md to reflect ProxySQL LLC as the new maintainer of orchestrator.

Changes

• Replace Percona fork notice with ProxySQL LLC maintainer statement
• Update lineage: Outbrain (2014) → GitHub (2016) → openark (2020) → Percona → ProxySQL LLC (2026)
• Update badge URLs from openark/orchestrator → proxysql/orchestrator
• Update documentation and logo links
• Add "Future Vision" section (ProxySQL-native integration, PostgreSQL exploration)
• Link to new governance files (CONTRIBUTING.md, CODE_OF_CONDUCT.md, SECURITY.md)
• Remove Percona-specific language and contact info

Acceptance Criteria

• All badge URLs point to proxysql/orchestrator
• No remaining references to openark/orchestrator or percona/orchestrator (except historical context)
• README clearly states ProxySQL LLC is the maintainer

[renecannao]

Done in PR #14