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/mpv.test.ts

@@ -529,6 +529,7 @@ function makeArgs(overrides: Partial<Args> = {}): Args {
     stats: false,
     doctor: false,
     doctorRefreshKnownWords: false,
+    version: false,
     configPath: false,
     configShow: false,
     mpvIdle: false,