Typed configuration.

Loads and fully validates configuration (file → environment → flags) before any socket opens, producing validated value objects the other crates consume (docs/01 §6). Invalid config fails fast with a typed, actionable [ConfigError] naming the bad field. It contains no business logic, it only turns strings into validated values; mapping those to domain types (the crypto provider, the pipeline) is the binary's job. Hot-reloadable state (directives, placement) goes through osproxy-control, not here.

Example

use osproxy_config::Config;
// Defaults apply when nothing is set; a bad value is a typed error.
let cfg = Config::resolve_for_test(&[("bind", "0.0.0.0:9000")]).unwrap();
assert_eq!(cfg.bind.port(), 9000);
assert!(cfg.require_tls_for_mutation, "enforced by default (NFR-S1)");
assert!(Config::resolve_for_test(&[("bind", "not-an-addr")]).is_err());