feat(launcher): add --version / -v flag to print app version

- Exits early with `SubMiner <version>` output, no app binary required
- Maps `-v` at root level without conflicting with `stats cleanup -v`
- Adds `version: boolean` to `Args` type and default args
- Documents flag in docs-site and adds changelog fragment

launcher/commands/playback-command.test.ts

@@ -52,6 +52,7 @@ function createContext(): LauncherCommandContext {
       stats: false,
       doctor: false,
       doctorRefreshKnownWords: false,
+      version: false,
       configPath: false,
       configShow: false,
       mpvIdle: false,