✨ (auth): Añade idioma y tema preferidos al usuario

- CurrentUser pasa de enum a struct con `id` opcional (anónimo = None) y
  preferencias de idioma, zona horaria y tema validadas en `with_*()`.
- `RequestLocale` tiene en cuenta el idioma preferido del usuario, y
  Context usa su tema si lo tiene (`default_theme()` en otro caso).
- Nuevos componentes `form::SelectLanguage`, `form::SelectTheme` y
  `form::SelectTimezone`, con `Timezone::supported_by_region()` para
  listar y validar las zonas IANA ofrecidas.

tests/auth.rs

@@ -4,7 +4,7 @@ use pagetop::prelude::*;
 
 #[pagetop::test]
 async fn anonymous_reports_itself_correctly() {
-    let user = CurrentUser::Anonymous;
+    let user = CurrentUser::anonymous();
     assert!(user.is_anonymous());
     assert!(!user.is_authenticated());
     assert_eq!(user.id(), None);
@@ -14,11 +14,7 @@ async fn anonymous_reports_itself_correctly() {
 #[pagetop::test]
 async fn authenticated_reports_itself_correctly() {
     let madrid: Tz = "Europe/Madrid".parse().unwrap();
-    let user = CurrentUser::Authenticated {
-        id: 42,
-        display_name: "Alice".to_owned(),
-        timezone: Some(madrid),
-    };
+    let user = CurrentUser::authenticated(42, "Alice").with_timezone("Europe/Madrid");
     assert!(!user.is_anonymous());
     assert!(user.is_authenticated());
     assert_eq!(user.id(), Some(42));
@@ -28,14 +24,39 @@ async fn authenticated_reports_itself_correctly() {
 
 #[pagetop::test]
 async fn authenticated_falls_back_to_default_timezone_when_none() {
-    let user = CurrentUser::Authenticated {
-        id: 42,
-        display_name: "Alice".to_owned(),
-        timezone: None,
-    };
+    let user = CurrentUser::authenticated(42, "Alice");
     assert_eq!(user.timezone(), Timezone::default_tz());
 }
 
+#[pagetop::test]
+async fn authenticated_discards_invalid_preferences() {
+    let user = CurrentUser::authenticated(42, "Alice")
+        .with_language("xx-XX")
+        .with_timezone("Mars/Olympus")
+        .with_theme("NotRegistered");
+    assert_eq!(user.language(), None);
+    assert_eq!(user.timezone(), Timezone::default_tz());
+    assert!(user.theme().is_none());
+}
+
+#[pagetop::test]
+async fn anonymous_can_have_preferences() {
+    let madrid: Tz = "Europe/Madrid".parse().unwrap();
+    let user = CurrentUser::anonymous()
+        .with_language("es-ES")
+        .with_timezone("Europe/Madrid");
+    assert!(user.is_anonymous());
+    assert_eq!(user.language(), Locale::resolve("es-ES").as_option());
+    assert_eq!(user.timezone(), madrid);
+}
+
+#[pagetop::test]
+async fn authenticated_resolves_language_to_a_supported_one() {
+    let user = CurrentUser::authenticated(42, "Alice").with_language("es");
+    assert_eq!(user.language(), Locale::resolve("es").as_option());
+    assert!(user.language().is_some());
+}
+
 // **< Context::current_user() >********************************************************************
 
 #[pagetop::test]
@@ -47,11 +68,7 @@ async fn current_user_defaults_to_anonymous() {
 #[pagetop::test]
 async fn current_user_propagates_from_request_extensions() {
     let req = web::test::TestRequest::get()
-        .with_extension(CurrentUser::Authenticated {
-            id: 7,
-            display_name: "Bob".to_owned(),
-            timezone: None,
-        })
+        .with_extension(CurrentUser::authenticated(7, "Bob"))
         .to_http_request();
     let cx = Context::new(req);
     let user = cx.current_user();
@@ -60,6 +77,52 @@ async fn current_user_propagates_from_request_extensions() {
     assert_eq!(user.display_name(), Some("Bob"));
 }
 
+#[pagetop::test]
+async fn user_language_sets_the_request_language() {
+    let req = web::test::TestRequest::get()
+        .header("Accept-Language", "en-US")
+        .with_extension(CurrentUser::authenticated(7, "Bob").with_language("es-ES"))
+        .to_http_request();
+    let cx = Context::new(req);
+    assert_eq!(cx.langid().to_string(), "es-ES");
+}
+
+#[pagetop::test]
+async fn lang_query_overrides_user_language() {
+    let req = web::test::TestRequest::get()
+        .uri("/?lang=en-US")
+        .with_extension(CurrentUser::authenticated(7, "Bob").with_language("es-ES"))
+        .to_http_request();
+    let cx = Context::new(req);
+    assert_eq!(cx.langid().to_string(), "en-US");
+}
+
+struct UserTheme;
+
+impl Extension for UserTheme {
+    fn theme(&self) -> Option<ThemeRef> {
+        Some(&UserTheme)
+    }
+}
+
+impl Theme for UserTheme {}
+
+#[pagetop::test]
+async fn user_theme_sets_the_context_theme() {
+    let _ = Application::prepare(&UserTheme).await;
+    let req = web::test::TestRequest::get()
+        .with_extension(CurrentUser::authenticated(7, "Bob").with_theme("UserTheme"))
+        .to_http_request();
+    let cx = Context::new(req);
+    assert_eq!(cx.theme().short_name(), "UserTheme");
+}
+
+#[pagetop::test]
+async fn context_uses_the_default_theme_without_user_theme() {
+    let cx = Context::default();
+    assert_eq!(cx.theme().short_name(), "Basic");
+}
+
 // **< HttpRequest::extension() >*******************************************************************
 
 #[pagetop::test]
@@ -71,11 +134,7 @@ async fn request_extension_returns_none_for_unknown_type() {
 #[pagetop::test]
 async fn request_extension_returns_injected_value() {
     let req = web::test::TestRequest::get()
-        .with_extension(CurrentUser::Authenticated {
-            id: 1,
-            display_name: "Carol".to_owned(),
-            timezone: None,
-        })
+        .with_extension(CurrentUser::authenticated(1, "Carol"))
         .to_http_request();
 
     let user = req
@@ -91,11 +150,7 @@ async fn request_extension_returns_injected_value() {
 #[pagetop::test]
 async fn page_new_propagates_current_user_from_request_extensions() {
     let req = web::test::TestRequest::get()
-        .with_extension(CurrentUser::Authenticated {
-            id: 5,
-            display_name: "Dave".to_owned(),
-            timezone: None,
-        })
+        .with_extension(CurrentUser::authenticated(5, "Dave"))
         .to_http_request();
     let page = Page::new(req);
     let user = page.current_user();