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/platform/lifecycle.ts

@@ -71,7 +71,7 @@ class TauriLifecycle implements PlatformLifecycle {
 
         // Check if server was started by this app instance
         // @ts-expect-error - accessing module-level variable from another module
-        const serverStartedByApp = window.__voiceboxServerStartedByApp ?? false;
+        const serverStartedByApp = window.__talkboxServerStartedByApp ?? false;
 
         console.log(
           '[lifecycle] window-close-requested: keepRunning=%s, serverStartedByApp=%s',