feat(codex): expose official routing and restore the built-in provider

Let users switch between the built-in OpenAI provider and third-party Codex providers directly from the provider panel while takeover mode remains active.

Centralize the frontend capability predicate so only the fixed codex-official seed receives native-login routing support, and keep copied UUID-based official entries clearly marked as unsupported.

Add an idempotent backend command that recreates the deleted official seed, wire it into the add-provider flow, refresh localized guidance, and add mutation and provider-action regression coverage.

src-tauri/src/database/dao/providers.rs

@@ -710,7 +710,9 @@ impl Database {
 #[cfg(test)]
 mod ensure_official_seed_tests {
     use crate::app_config::AppType;
-    use crate::database::{Database, CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID};
+    use crate::database::{
+        Database, CLAUDE_DESKTOP_OFFICIAL_PROVIDER_ID, CODEX_OFFICIAL_PROVIDER_ID,
+    };
 
     #[test]
     fn ensure_inserts_when_missing() {
@@ -769,6 +771,25 @@ mod ensure_official_seed_tests {
         );
     }
 
+    #[test]
+    fn ensure_recreates_codex_official_seed_after_deletion() {
+        let db = Database::memory().expect("memory db");
+        db.init_default_official_providers().expect("seed");
+        db.delete_provider(AppType::Codex.as_str(), CODEX_OFFICIAL_PROVIDER_ID)
+            .expect("delete Codex official");
+
+        let inserted = db
+            .ensure_official_seed_by_id(CODEX_OFFICIAL_PROVIDER_ID, AppType::Codex)
+            .expect("ensure Codex official");
+        assert!(inserted);
+        let provider = db
+            .get_provider_by_id(CODEX_OFFICIAL_PROVIDER_ID, AppType::Codex.as_str())
+            .expect("query")
+            .expect("Codex official restored");
+        assert_eq!(provider.category.as_deref(), Some("official"));
+        assert_eq!(provider.settings_config["auth"], serde_json::json!({}));
+    }
+
     #[test]
     fn ensure_rejects_unknown_seed() {
         let db = Database::memory().expect("memory db");