- session/config.rs: add SessionConfig struct that pre-validates all
session configuration values, with build_middleware() for infallible
middleware construction
- session/middleware.rs: expose parse_same_site as pub(crate)
- session/storage/redis.rs: derive Clone for RedisSessionStore
- main.rs: validate session config before HttpServer loop, use
SessionConfig::build_middleware() inside closure; add
sqlx::migrate!() call after database connection
zhenyi