fix(settings): language picker breaks on a server locale not in our list

Live warning: "en_GB" invalid tag, undefined Picker display — the curated
OutlineLocale.all didn't include it. Added en_GB explicitly, and made the
Picker's item list always include whatever code the server actually
reports (falling back to the code itself as the label) so any future
unlisted locale degrades gracefully instead of breaking the control.

Outpost/Features/Account/SettingsView.swift

@@ -375,7 +375,7 @@ struct SettingsView: View {
                     ProgressView().controlSize(.small)
                 } else {
                     Picker("Language", selection: languageBinding) {
-                        ForEach(OutlineLocale.all) { locale in
+                        ForEach(displayedLocales) { locale in
                             Text(locale.label).tag(locale.code)
                         }
                     }
@@ -443,6 +443,20 @@ struct SettingsView: View {
         )
     }
 
+    /// `OutlineLocale.all` is a curated subset, not Outline's full list —
+    /// a self-hosted server can report a code we don't know about (seen
+    /// live: "en_GB"). `Picker` needs a `Text` for every possible selection
+    /// or it logs "invalid tag" and its displayed value goes undefined —
+    /// appending the current code here (using itself as the label, same
+    /// fallback `OutlineLocale.label(for:)` already uses) guarantees a
+    /// match no matter what the server sends.
+    private var displayedLocales: [OutlineLocale] {
+        guard let current = session.userLanguage, !OutlineLocale.all.contains(where: { $0.code == current }) else {
+            return OutlineLocale.all
+        }
+        return OutlineLocale.all + [OutlineLocale(code: current, label: OutlineLocale.label(for: current))]
+    }
+
     private var languageBinding: Binding<String> {
         Binding(
             get: { session.userLanguage ?? "en_US" },

Outpost/Support/OutlineLocale.swift

@@ -13,6 +13,7 @@ struct OutlineLocale: Identifiable, Hashable {
 
     static let all: [OutlineLocale] = [
         OutlineLocale(code: "en_US", label: "English (US)"),
+        OutlineLocale(code: "en_GB", label: "English (UK)"),
         OutlineLocale(code: "de_DE", label: "Deutsch"),
         OutlineLocale(code: "fr_FR", label: "Français"),
         OutlineLocale(code: "es_ES", label: "Español"),