feat(0.6.2): current version badge on Settings page

Small grey pill follows the "Radio — Settings" H1 — v{RADIO_VERSION}.
Visible at a glance so you don't have to hover the plugin row in
Plugins → Installed or open About just to check what version you're on.
Dark-theme variant so it stays readable when theme=dark.

Files: radio.php (version), inc/settings.php (<span> inside H1),
assets/css/radio.css (.radio-version-badge + dark override),
inc/about.php (rotate v0.6.2 into latest expanded slot, v0.6.1 into
earlier-releases list), CHANGELOG.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

radio.php

@@ -5,7 +5,7 @@
  * Plugin Name: Radio
  * Plugin URI:  https://icanhelp.ie/radio
  * Description: A small, focused, free radio player for your WordPress admin. 44 SomaFM stations grouped by 10 genres — ambient, electronic, lounge, rock, metal, jazz, world, reggae, holiday, specials. Plays via HTML5 audio; volume + station choice persist per-user.
- * Version:     0.6.1
+ * Version:     0.6.2
  * Requires at least: 5.0
  * Requires PHP: 7.4
  * Author:      David Keane
@@ -20,7 +20,7 @@
 if ( ! defined( 'ABSPATH' ) ) { exit; }
 
 // Plugin coordinates.
-if ( ! defined( 'RADIO_VERSION' ) )   { define( 'RADIO_VERSION',   '0.6.1' ); }
+if ( ! defined( 'RADIO_VERSION' ) )   { define( 'RADIO_VERSION',   '0.6.2' ); }
 if ( ! defined( 'RADIO_FILE' ) )      { define( 'RADIO_FILE',      __FILE__ ); }
 if ( ! defined( 'RADIO_PATH' ) )      { define( 'RADIO_PATH',      plugin_dir_path( __FILE__ ) ); }
 if ( ! defined( 'RADIO_URL' ) )       { define( 'RADIO_URL',       plugin_dir_url( __FILE__ ) ); }