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

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

schema.sql

@@ -7,6 +7,7 @@ CREATE TABLE IF NOT EXISTS "sessions" (
     "totp_pending" BOOLEAN NOT NULL,
     "oauth_groups" TEXT NULL,
     "expiry" INTEGER NOT NULL,
+    "created_at" INTEGER NOT NULL,
     "oauth_name" TEXT NULL,
     "oauth_sub" TEXT NULL
 );