Drop the Radio icon from Context and make the panel easier to read

The Context header carried a Radio icon that opened a second, compact
Radio player on top of the panel, duplicating the Radio section that
already lives inside Context. Remove the icon, the compact player and
everything that kept the two in step. Radio stays in Context as its own
section with one Enable control; Cockpit's compact Radio is unchanged.

Context itself was hard to read: 7-8 px labels at low contrast, a dashed
placeholder box, and a glow halo. The two modes are now one segmented
control, labels and guidance are 10 px at higher contrast, the standby
hint is plain text, section titles use --text-secondary, and the panel
draws no glow.

Unused translations are pruned, tests and QA harnesses that pinned the
compact player are updated or retired, and CURRENT-STATE and the
changelog describe the new header.

src/i18n/locales/zh-Hant.json

@@ -1848,10 +1848,6 @@
   "STATION UNAVAILABLE": "電臺不可用",
   "Station unavailable after directory refresh": "目錄刷新後該電臺不可用",
   "Radio could not {action} cleanly": "電臺未能正常{action}",
-  "Go to expanded Radio section": "前往展開的電臺區域",
-  "Expand Radio section in Context": "在態勢面板中展開電臺區域",
-  "Close compact Radio controls": "關閉精簡電臺控件",
-  "Open compact Radio controls": "打開精簡電臺控件",
   "SYNC": "同步",
   "RECONCILE": "核對",
   "DISABLE": "停用",
@@ -1873,9 +1869,6 @@
   "selected": "所選",
   "nearest": "最近",
   "{action} {target} radio station": "{action}{target}電臺",
-  "RADIO STATE UNCERTAIN": "電臺狀態不確定",
-  "SYNCING DIRECTORY": "正在同步目錄",
-  "RADIO READY": "電臺就緒",
   "SYNCING": "同步中",
   "READY": "就緒",
   "station": "電臺",
@@ -2539,11 +2532,6 @@
   "RECENT IMAGERY": "近期影像",
   "Imagery days in the box": "視野內的影像天數",
   "CONTEXT": "態勢",
-  "Compact Radio controls": "精簡電臺控件",
-  "Open detailed Radio controls": "打開詳細電臺控件",
-  "Previous station": "上一個電臺",
-  "Next station": "下一個電臺",
-  "Compact Radio volume": "精簡電臺音量",
   "Expand panel": "展開面板",
   "Context mode": "態勢模式",
   "CONTACTS": "目標",