refactor: simplify Timestamp and RightClickRestorer

Timestamp:
- Extract shared utilities (msToUnit, dayjsFromTimestamp, ModeType)
- Remove unnecessary useCallback/useMemo/React.memo
- Remove extra info section (relative time, ISO 8601, UTC)
- Fix missing translation key timestamp_unitS

RightClickRestorer:
- Remove website badge (右键已解锁 overlay)
- Remove mouse penetration logic for media elements
- Remove unnecessary useCallback
- Remove redundant setIsLoading call

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/_locales/zh/messages.json

@@ -760,6 +760,10 @@
     "message": "毫秒 (ms)",
     "description": "Translation key: timestamp_unitMs"
   },
+  "timestamp_unitS": {
+    "message": "秒 (s)",
+    "description": "Translation key: timestamp_unitS"
+  },
   "timestamp_currentTs": {
     "message": "当前时间戳",
     "description": "Translation key: timestamp_currentTs"