Add http feature flag with axum, hyper, hyper-util, tower, and http-body-util
dependencies. Create http module with auth middleware (extracts Bearer token,
calls IdentityProvider::resolve_from_token, attaches Identity to extensions)
and router scaffold (default 404 fallback, no operational routes yet). Replace
send_fake_nginx_404 with axum router handoff when http feature is enabled;
fake 404 behavior preserved when http is disabled. Wire HttpInterface with
build_router() method and pass IdentityProvider through Server to handle_connection.
ConfigServiceImpl wraps ArcSwap<DynamicConfig> providing forwarding_policy(),
rate_limits(), and reload() methods for direct use (always available).
ConfigProtocol enum (GetForwardingPolicy, GetRateLimits, ReloadForwarding,
ReloadRateLimits) is gated behind the irpc feature flag per ADR-030.
Split alknet-core configuration into StaticConfig (immutable after startup)
and DynamicConfig (hot-reloadable at runtime via ArcSwap).
- Add StaticConfig struct in config/static_config.rs with all fields per ADR-030
- Add DynamicConfig struct with AuthPolicy, ForwardingPolicy, RateLimitConfig
- Add ForwardingPolicy with allow_all()/deny_all() defaults (ADR-031)
- Add ConfigReloadHandle with reload() method for runtime config updates
- Replace Arc<ServerAuthConfig> with Arc<ArcSwap<DynamicConfig>> in ServerHandler
- Add config_reload_handle() to Server for obtaining reload handles
- Add AuthPolicy with authenticate_publickey/authenticate_certificate methods
- All existing tests pass with the new config structure
- Default DynamicConfig produces identical behavior to current code
