Clarify Feishu app setup and OpenVPN OIDC source

frontend/src/locales/en-US.json

@@ -229,23 +229,27 @@
     "title": "Feishu / OIDC browser authentication",
     "externalService": "Requires openvpn-auth-oauth2",
     "componentReady": "Authentication component installed v{version}",
-    "authEntryPending": "HTTPS is ready at {domain}; the auth component's public callback route is not yet connected and an OIDC issuer is still needed.",
+    "authEntryPending": "HTTPS is ready at {domain}; sync the authentication route in Settings → Feishu Identity after starting the tunnel.",
     "app": "Create app",
     "appShort": "Feishu developer console",
     "identity": "Enter identity settings",
     "identityShort": "OIDC and credentials",
+    "builtinIdentityShort": "Enter Feishu credentials in Settings",
     "callback": "Set public callback",
     "callbackShort": "HTTPS reverse proxy",
     "test": "Test client",
     "testShort": "Browser sign-in",
     "appTip": "Ask a Feishu administrator to create and publish an app with the appropriate sign-in capability.",
+    "builtinAppTip": "Manage Feishu App ID and App Secret in Settings → Feishu Identity, not in each tunnel.",
     "openConsole": "Open Feishu app console",
     "appInstruction1": "Create an enterprise app, obtain its credentials, and enable the web sign-in capability.",
     "appInstruction2": "Register a redirect URL under the app's security/redirect settings. If using a broker, use the broker's upstream callback here.",
+    "builtinAppInstruction2": "Register the Feishu app callback shown below in the app's redirect settings, not the VPN client callback.",
     "appInstruction3": "Publish the app and restrict its available users to people allowed to access this VPN.",
     "scopeTip": "Restrict who can use the Feishu app. LDAP dial-in users are not automatically linked to Feishu identities.",
     "providerTip": "Use the built-in Feishu issuer configured in Settings, or provide an external issuer with OIDC discovery and ID tokens. A Feishu app URL alone is not an issuer.",
-    "useBuiltIn": "Use built-in Feishu issuer", "builtInSecret": "The VPN client secret is supplied internally by the server and never returned on this page.", "builtInGatewayPending": "The public Nginx route for the built-in issuer is pending; sync it in Settings before testing.",
+    "source": "Identity source", "builtinSource": "Built-in Feishu", "externalSource": "External OIDC", "configureBuiltIn": "The built-in Feishu issuer is not enabled. Save app credentials and enable it in Settings first.", "manageFeishu": "Open Settings → Feishu Identity", "builtinSummary": "The Feishu App ID, App Secret, and tenant are managed in Settings; this tunnel references the issuer and its own public authentication entry.",
+    "useBuiltIn": "Use built-in Feishu issuer", "builtInSecret": "The server supplies the VPN Client Secret. Do not enter the Feishu App Secret here.", "builtInGatewayPending": "The public Nginx route for the built-in issuer is pending; sync it in Settings before testing.",
     "issuer": "OIDC issuer URL",
     "issuerTip": "Use an HTTPS issuer that provides standard discovery (/.well-known/openid-configuration) and ID tokens, not an authorization page URL.",
     "clientId": "OIDC Client ID",
@@ -256,15 +260,17 @@
     "secretTip": "Encrypted server-side and stored only in the auth service's 0600 configuration file.",
     "baseUrl": "Public sign-in URL",
     "baseTip": "Automatic filling reuses the domain and certificate only. The management site does not yet proxy OAuth2 paths to the auth component. Sign-in needs that Nginx route. Recheck saved tunnel callbacks if the domain changes.",
+    "builtinBaseTip": "Uses the system HTTPS domain automatically. The auth component listens locally; sync public routes in Settings after starting the tunnel.",
     "reuseDomain": "Use current public domain", "linkedDomain": "Using the HTTPS domain from system settings; you can edit it.",
     "listenPort": "Local auth service port",
     "portTip": "Listens only on 127.0.0.1; no public access needed. New tunnels increment from 19090; +/- and manual entry skip configured and locally occupied ports.",
     "portLookupFailed": "Could not find an available port. Retry or enter one manually.",
     "callbackTitle": "Register this callback with the final OIDC provider",
     "callbackTip": "With an identity broker, register this URL in the broker's OIDC client, and register the broker's upstream callback in Feishu. Reverse proxy the public endpoint to 127.0.0.1:{port}; :18080 does not handle this callback.",
+    "builtinCallbackTitle": "The VPN client and Feishu app use different callbacks", "builtinCallbackTip": "The VPN client callback above is handled by openvpn-auth-oauth2. Register only the Feishu app callback below in Feishu. After starting the tunnel, sync /oauth2/ to local port 127.0.0.1:{port} in Settings.", "feishuCallbackLabel": "Feishu app callback",
     "testTip": "Install openvpn-auth-oauth2 and OpenVPN ≥ 2.6.2, then test with a WebAuth-capable client (e.g. OpenVPN Community for Windows or Tunnelblick/Viscosity for macOS). OpenVPN Connect v3 needs individual testing.",
     "startFailed": "Configuration generated, but the tunnel did not start. Resolve the error below and retry from the tunnel list.",
-    "fillRequired": "Enter the OIDC issuer, app credentials, and public sign-in URL"
+    "fillRequired": "Configure an identity source, OIDC issuer, VPN client credentials, and public sign-in URL"
   },
   "tunnelEditor": {
     "title": "Edit Tunnel",
@@ -569,7 +575,7 @@
   },
   "identity": {
     "tab": "Feishu identity", "title": "Built-in Feishu identity service", "description": "Issue OIDC identities for VPN using your existing HTTPS domain. Feishu app credentials stay upstream; this platform creates separate VPN client credentials.",
-    "appId": "Feishu App ID", "appSecret": "Feishu App Secret", "secretPlaceholder": "Leave blank to retain the secret; use a rotated secret for new setup", "tenant": "Allowed Feishu tenant_key", "tenantPlaceholder": "Verify the enterprise tenant_key from Feishu user info", "enabled": "Enable built-in issuer",
+    "appId": "Feishu App ID", "appSecret": "Feishu App Secret", "secretPlaceholder": "Leave blank to retain the secret; use a rotated secret for new setup", "tenant": "Allowed Feishu tenant_key", "tenantPlaceholder": "Verify the enterprise tenant_key from Feishu user info", "enabled": "Enable built-in issuer", "httpsOnly": "Enter app credentials only through the HTTPS management site. Switch to its secure address.", "openHttps": "Open HTTPS management site",
     "httpsRequired": "Configure and activate your public HTTPS site and certificate first.", "gatewayPending": "The identity provider is saved but Nginx does not yet route /id/; sync the gateway.",
     "addresses": "Addresses and client credentials", "issuer": "OIDC issuer", "feishuCallback": "Callback registered in Feishu", "vpnCallback": "VPN client callback", "clientId": "VPN Client ID",
     "oneTimeSecret": "New VPN Client Secret is displayed only once. Store it safely; rotation of active tunnel credentials requires separate planning.", "routeHint": "Sync identity routes first. After starting the one OpenVPN OIDC tunnel using this domain, sync again to route /oauth2/ to its local auth component.",