feat: v0.2.0 — UI rebuilt to WordPress admin standards

v0.1.0 worked but felt like a third-party React widget bolted on
top of WordPress. v0.2.0 makes the player visually native to the
WP admin: postbox container, standard Play/Pause button with text
label, admin-colour-scheme aware accents, dashboard widget no
longer renders a card inside a card.

CHANGES
- inc/admin-page.php: main page now wraps the player in a
  .postbox > .postbox-header (with h2.hndle) > .inside structure.
  Custom rounded card / shadow stripped.
- inc/dashboard-widget.php: bare .radio-player content; WP already
  wraps dashboard widgets in a postbox, was double-card before.
- inc/about.php: version-history card promotes v0.2.0 to latest,
  demotes v0.1.0.
- assets/css/radio.css: rewrite. Strip custom shadows + oversized
  typography. Adopt WP body-text defaults. Use
  var(--wp-admin-theme-color, #2271b1) for volume-slider accent +
  link colours so the plugin picks up whichever admin colour
  scheme the user has chosen. About-page cards now use the
  postbox-style gray header + 1px border pattern.
- assets/js/radio.js: setPlayIcon() also flips the visible text
  label ("Play" ↔ "Pause"), not just the icon class. mirrorSelection()
  also updates the [data-radio-genre] element so the genre label
  stays in sync across surfaces.
- radio.php: Version: 0.1.0 -> 0.2.0; BUDDY_VERSION constant
  bumped likewise.
- CHANGELOG.md: new [0.2.0] entry explaining the visual overhaul.

NET EFFECT
- Same 44 stations, same audio path, same persistence, same
  updater, same AJAX endpoint. Pure visual change.
- The plugin now looks like part of WordPress admin instead of a
  guest widget.
- Closer to WP.org submission criteria — plugin reviewers look
  for native-styled plugins.

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:     0.1.0
+ * Version:     0.2.0
  * 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',  '0.1.0' ); }
+if ( ! defined( 'RADIO_VERSION' ) )  { define( 'RADIO_VERSION',  '0.2.0' ); }
 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__ ) ); }