chore(release): bump version 0.4.1 → 0.4.2

tauri-action uses tauri.conf.json's version to name the release, so
pushing v0.4.2 as a tag alone was insufficient — the workflow was still
trying to publish to v0.4.1 (immutable) and failing. Bumps all workspace
package.json files, Cargo.toml, Cargo.lock, and tauri.conf.json.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

tauri/src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "Voicebox",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "identifier": "sh.voicebox.app",
   "build": {
     "beforeDevCommand": "bun run dev",