tools: add sync-version.js to sync package.json -> Tauri files

- Add tools/sync-version.js script to read root package.json version
  and update src-tauri/tauri.conf.json and src-tauri/Cargo.toml.
- Update only the [package] version line in Cargo.toml to preserve formatting.
- Include JSON read/write helpers and basic error handling/reporting.

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "radio-tauri"
-version = "0.1.0"
+version = "0.1.1"
 description = "A Tauri App"
 authors = ["you"]
 edition = "2021"