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

tauri/src-tauri/tests/audio_capture_test.rs

@@ -4,7 +4,7 @@
 //   2. Run: cargo test --test audio_capture_test -- --nocapture
 //   3. The test will capture audio for 5 seconds and verify the output
 
-use voicebox::audio_capture::{AudioCaptureState, start_capture, stop_capture};
+use talkbox::audio_capture::{AudioCaptureState, start_capture, stop_capture};
 use base64::Engine;
 
 #[tokio::test]