rebrand: rename VoiceBox to TalkBox throughout codebase

- All 'voicebox'/'Voicebox'/'VOICEBOX' strings replaced with 'talkbox'/'TalkBox'/'TALKBOX'
- Port changed from 17493 to 17494 (avoids conflict with upstream VoiceBox)
- MCP tool namespace: voicebox.* -> talkbox.*
- App bundle ID: sh.voicebox.app -> com.talkbox.app
- Binary names: voicebox-server -> talkbox-server, voicebox-mcp -> talkbox-mcp
- Docker user/group: voicebox -> talkbox
- Database: voicebox.db -> talkbox.db
- Env vars: VOICEBOX_* -> TALKBOX_*
- Asset files renamed: voicebox-logo.* -> talkbox-logo.*, etc.
- External binaries in tauri.conf.json updated to talkbox-server/talkbox-mcp

backend/README.md

@@ -1,4 +1,4 @@
-# Voicebox Backend
+# TalkBox Backend
 
 FastAPI server powering voice cloning, speech generation, and audio processing. Runs locally as a Tauri sidecar or standalone via `python -m backend.main`.
 
@@ -9,7 +9,7 @@ FastAPI server powering voice cloning, speech generation, and audio processing.
 just dev:server
 
 # Standalone
-python -m backend.main --host 127.0.0.1 --port 17493
+python -m backend.main --host 127.0.0.1 --port 17494
 
 # With custom data directory
 python -m backend.main --data-dir /path/to/data
@@ -75,7 +75,7 @@ Detection is handled by `utils/platform_detect.py`. Both backends implement the
 
 ## API
 
-90 endpoints organized by domain. Full interactive documentation available at `http://localhost:17493/docs` when the server is running.
+90 endpoints organized by domain. Full interactive documentation available at `http://localhost:17494/docs` when the server is running.
 
 | Domain | Prefix | Description |
 |--------|--------|-------------|
@@ -96,29 +96,29 @@ Detection is handled by `utils/platform_detect.py`. Both backends implement the
 
 ```bash
 # Generate speech
-curl -X POST http://localhost:17493/generate \
+curl -X POST http://localhost:17494/generate \
   -H "Content-Type: application/json" \
   -d '{"text": "Hello world", "profile_id": "...", "language": "en"}'
 
 # List profiles
-curl http://localhost:17493/profiles
+curl http://localhost:17494/profiles
 
 # Stream generation status (SSE)
-curl http://localhost:17493/generate/{id}/status
+curl http://localhost:17494/generate/{id}/status
 ```
 
 ## Data directory
 
 ```
 {data_dir}/
-  voicebox.db             # SQLite database
+  talkbox.db             # SQLite database
   profiles/{id}/          # Voice samples per profile
   generations/            # Generated audio files
   cache/                  # Voice prompt cache (memory + disk)
   backends/               # Downloaded CUDA binary (if applicable)
 ```
 
-Default location is the OS-specific app data directory. Override with `--data-dir` or the `VOICEBOX_DATA_DIR` environment variable.
+Default location is the OS-specific app data directory. Override with `--data-dir` or the `TALKBOX_DATA_DIR` environment variable.
 
 ## Code quality