Auth strategies (JWT/OAuth2, Key, Casbin) (Middlewares — P2)

[meshin-dev]

• What: Pluggable authentication/authorization middlewares (JWT validation, OAuth2 token verification, RBAC).
• Why Middlewares: Policy‑heavy, many ecosystems.
• Precedents: Echo JWT/Casbin; Chi OAuth packages; numerous Gin contribs. (echo.labstack.com], [GoChi Oauth])
• When possible use third-party libraries especially if they combine few auth methods in one universal library, compatible with net/http