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/README.md

@@ -54,7 +54,7 @@ frontend supplies its own UI and audio backend while reusing `core` unchanged.
 - Configurable capture/playback **devices**.
 
 ### Server interaction
-- Connect to any TS3 server (auto-generates and persists a TS3 identity).
+- Connect to any TS3 server (an identity is generated on first use if none exists).
 - **Channel/client tree** styled like TS3, updated live from protocol events
   (joins, leaves, moves, channel create/edit/delete, nickname/mute/away changes).
 - **Talk indicators** — speakers turn green live as they talk.
@@ -68,7 +68,11 @@ frontend supplies its own UI and audio backend while reusing `core` unchanged.
   **private chat**, or **locally mute** them.
 - **Chat** to the current channel or the whole server; receive channel/server/private
   messages and **pokes**.
-- **Server bookmarks** — quick-connect menu with add/edit/remove management.
+- **Server bookmarks** — quick-connect menu with add/edit/remove management, each
+  optionally pinned to a specific identity.
+- **Identity management** (Tools → Identities) — keep several identities, mark one
+  as the default, pick one per server or per bookmark, rename, raise an identity's
+  security level, and import/export TeamSpeak-compatible `.ini` identity files.
 - **Self status** — Away (with message) and Channel Commander toggles.
 - **Status bar** shows the server name, user count and live ping.
 - Change your nickname, mute/deafen from the toolbar.
@@ -97,15 +101,16 @@ java -jar swing/target/ts3-client.jar
 mvn -pl swing exec:java
 ```
 
-Then use **Connections → Connect…**, enter a server address, port (default 9987)
-and nickname, and connect. Open **Tools → Options** to pick audio devices and tune
+Then use **Connections → Connect…**, enter a server address, port (default 9987),
+nickname and identity, and connect. Open **Tools → Options** to pick audio devices and tune
 voice activation while watching the live meter.
 
 ## Architecture
 ```
 core/   com.ts3client
 ├── config.Settings          persisted prefs (~/.ts3jclient/settings.properties)
-├── config.Bookmarks         persisted server bookmarks
+├── config.Bookmarks         persisted server bookmarks (with per-server identity)
+├── config.IdentityStore     managed identities (~/.ts3jclient/identities/*.ini)
 ├── audio                    abstractions + reusable DSP (no platform code)
 │   ├── AudioBackend         factory for a platform's VoiceInput/VoiceOutput
 │   ├── VoiceInput           capture source (extends ts3j Microphone) + gating controls
@@ -137,6 +142,8 @@ swing/  com.ts3client
     ├── SettingsDialog       audio + VAD options with live meter
     ├── ConnectDialog        connect form
     ├── BookmarksDialog      manage saved servers
+    ├── IdentitiesDialog     manage identities (new/import/export/improve)
+    ├── IdentityChooser      identity drop-down shared by connect/bookmark forms
     ├── LevelMeter           dBFS meter with threshold marker
     ├── Icons                programmatic vector icons (no image assets)
     └── Theme                palette + fonts