feat: add session max lifetime and fix refresh logic (#559)

* feat: allow any HTTP method for /api/auth/envoy and restrict methods for non-envoy proxies

* feat: add Allow header for invalid methods in proxyHandler

* feat: add session max lifetime and fix refresh logic

* fix: set default value for created_at column and improve session expiration logic

---------

Co-authored-by: Stavros <steveiliop56@gmail.com>

internal/repository/models.go

@@ -13,6 +13,7 @@ type Session struct {
 	TotpPending bool
 	OAuthGroups string
 	Expiry      int64
+	CreatedAt   int64
 	OAuthName   string
 	OAuthSub    string
 }