Draw the interface with TeamSpeak icon packs

Icon packs are read in TeamSpeak's own format — a zip (or unpacked folder)
of SVG/PNG art plus a settings.ini mapping icon keys to files — so the packs
of an installed client and the ones from its add-on site work unchanged.
Legacy packs without that mapping (default.zip) are resolved by their file
naming convention instead, picking the resolution closest to the drawn size.

The pack draws the tree, toolbar, menus, context menus, file browser and the
default group icons; a pack's FALLBACK option decides whether what it lacks
comes from default.zip, and anything still missing falls back to the icons
the client draws itself. Options → Design picks the pack and shows a viewer
of everything in it.

Vector art is rasterised with JSVG, and the pack search roots are shared
with the sound packs.

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

ts3-client/README.md

@@ -93,6 +93,21 @@ frontend supplies its own UI and audio backend while reusing `core` unchanged.
 - Sounds are mixed onto one playback line, so overlapping events never fight over
   the device; pack volume is separate from the voice volume.
 
+### Icon packs
+- **Icon packs** in TeamSpeak's own format: a `.zip` (or unpacked folder) of SVG/PNG
+  artwork plus a `settings.ini` mapping icon keys (`CHANNEL_GREEN`, `PLAYER_ON`,
+  `CONNECT`, …) to files. Packs are picked up from `~/.ts3jclient/gfx`, an installed
+  TeamSpeak 3 client (`$TS3_CLIENT_DIR` or the usual install paths) and a folder of
+  your choosing, so the official packs (`default_colored_2014.zip`,
+  `default_mono_2014.zip`, the legacy `default.zip`) work unchanged.
+- The pack draws the tree (server, channel, client state), the toolbar, the menus,
+  the context menus, the file browser and TeamSpeak's default group icons. Vector
+  art is rasterised at the size it is drawn at; a pack's `FALLBACK` option decides
+  whether icons it lacks come from `default.zip`, and anything still missing falls
+  back to the icons the client draws itself.
+- **Pick one in Options → Design**, which also shows a viewer of everything the pack
+  contains; switching redraws the window right away.
+
 ## Requirements
 - Java 26+ (developed/tested on Temurin 26)
 - The native Opus library on the system:
@@ -133,6 +148,9 @@ core/   com.ts3client
 │   ├── VoiceOutput          voice-packet playback sink
 │   ├── OpusParameters       live-tunable encoder settings
 │   └── SpeechDetector       feature-based speech-probability VAD (Automatic/Hybrid)
+├── gfx
+│   ├── IconPack             an icon pack zip/folder + its settings.ini mapping
+│   └── IconPacks            discovery of installed packs
 ├── sound
 │   ├── SoundEvent           catalogue of actions (TeamSpeak's own event ids)
 │   ├── SoundPack            a pack folder + its settings.ini mapping
@@ -165,12 +183,14 @@ swing/  com.ts3client
     ├── ChatPanel            chat log + input
     ├── SettingsDialog       audio + VAD options with live meter
     ├── NotificationsPanel   sound pack + per-action sound/important configuration
+    ├── IconPackPanel        icon pack chooser + icon viewer (Options → Design)
     ├── 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)
+    ├── IconTheme            active icon pack: rasterising (JSVG) and caching
+    ├── Icons                icon lookup by TeamSpeak key, with drawn fallbacks
     └── Theme                palette + fonts
 ```
 
@@ -178,7 +198,6 @@ swing/  com.ts3client
 - The **Automatic/Hybrid** VAD uses a lightweight energy/spectral detector rather
   than the WebRTC GMM model the official client ships; it is intentionally
   dependency-free and reusable in the core library.
-- Group display shows names; **group icons** are not rendered.
 - Whisper is received/played but not yet **sendable** from the UI.
 - Playback decodes streams as mono; stereo music-bot audio is down-mixed.
 - Push-to-talk is captured via Swing key events, so it only works while the app