Add identity management

Manage several TeamSpeak identities like the official client instead of
using one auto-generated identity file.

- IdentityStore/IdentityEntry keep each identity as a TeamSpeak-format INI
  in ~/.ts3jclient/identities, so files interchange with the TS3 client;
  supports create, import, export, rename, remove and a cancellable
  security-level search. A legacy identity.ini is migrated in on first load.
- Settings hold the default identity; bookmarks may pin their own, falling
  back to the default when unset.
- TeamspeakConnection now connects with the identity it is handed.
- Swing: Tools -> Identities manager, plus an identity drop-down in the
  connect and bookmark forms.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ts3-client/swing/src/main/java/com/ts3client/ui/ConnectDialog.java

@@ -1,5 +1,6 @@
 package com.ts3client.ui;
 
+import com.ts3client.config.IdentityStore;
 import com.ts3client.config.Settings;
 
 import javax.swing.BorderFactory;
@@ -23,10 +24,11 @@ public final class ConnectDialog extends JDialog {
     private final JTextField portField;
     private final JTextField nickField;
     private final JPasswordField passwordField;
+    private final IdentityChooser identityChooser;
 
     private boolean confirmed;
 
-    public ConnectDialog(Frame owner, Settings settings) {
+    public ConnectDialog(Frame owner, Settings settings, IdentityStore identities) {
         super(owner, "Connect to Server", true);
 
         String addr = settings.lastAddress;
@@ -44,6 +46,7 @@ public final class ConnectDialog extends JDialog {
         portField = new JTextField(Integer.toString(port), 6);
         nickField = new JTextField(settings.nickname, 18);
         passwordField = new JPasswordField(settings.serverPassword, 18);
+        identityChooser = new IdentityChooser(identities, false, settings.defaultIdentityId);
 
         JPanel form = new JPanel(new GridBagLayout());
         form.setBorder(BorderFactory.createEmptyBorder(12, 12, 8, 12));
@@ -57,6 +60,7 @@ public final class ConnectDialog extends JDialog {
         add(form, c, row++, "Port:", portField);
         add(form, c, row++, "Nickname:", nickField);
         add(form, c, row++, "Password (optional):", passwordField);
+        add(form, c, row++, "Identity:", identityChooser);
 
         JPanel buttons = new JPanel(new BorderLayout());
         JPanel right = new JPanel();
@@ -116,4 +120,9 @@ public final class ConnectDialog extends JDialog {
     public String getPassword() {
         return new String(passwordField.getPassword());
     }
+
+    /** Chosen identity id, or an empty string to fall back to the default identity. */
+    public String getIdentityId() {
+        return identityChooser.getSelectedIdentityId();
+    }
 }