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/main.ts

@@ -1,4 +1,5 @@
 import path from 'node:path';
+import packageJson from '../package.json';
 import {
   loadLauncherJellyfinConfig,
   loadLauncherMpvConfig,
@@ -20,6 +21,11 @@ import { runJellyfinCommand } from './commands/jellyfin-command.js';
 import { runPlaybackCommand } from './commands/playback-command.js';
 import { runUpdateCommand } from './commands/update-command.js';
 
+const APP_VERSION =
+  typeof packageJson.version === 'string' && packageJson.version.trim()
+    ? packageJson.version
+    : 'unknown';
+
 function createCommandContext(
   args: ReturnType<typeof parseArgs>,
   scriptPath: string,
@@ -56,6 +62,12 @@ async function main(): Promise<void> {
   const launcherConfig = loadLauncherYoutubeSubgenConfig();
   const launcherMpvConfig = loadLauncherMpvConfig();
   const args = parseArgs(process.argv.slice(2), scriptName, launcherConfig, launcherMpvConfig);
+
+  if (args.version) {
+    console.log(`SubMiner ${APP_VERSION}`);
+    return;
+  }
+
   const pluginRuntimeConfig = readPluginRuntimeConfig(args.logLevel);
   const appPath = findAppBinary(scriptPath);