fix: ganti warna desc diskusi dan pindahkan inline styles ke styles.ts

- Ganti warna teks deskripsi dari dimmed ke text pada list diskusi umum dan divisi
- Tambah class discussionHeaderPadding, discussionListPadding, discussionTitleCol,
  discussionDescMargin, discussionEmptyText ke component.styles.ts
- Ganti semua inline style dengan themed object (warna dinamis) dan Styles.* (statis)

constants/styles/component.styles.ts

@@ -86,6 +86,11 @@ const ComponentStyles = StyleSheet.create({
    discussionDateText: { fontSize: 11 },
    discussionCommentCard: { borderRadius: 10, borderWidth: 1, padding: 12, marginBottom: 8, flexDirection: 'row' },
    discussionEditedText: { fontSize: 10, fontStyle: 'italic' },
+   discussionHeaderPadding: { paddingTop: 12 },
+   discussionListPadding: { paddingTop: 8 },
+   discussionTitleCol: { marginLeft: 10 },
+   discussionDescMargin: { marginBottom: 10 },
+   discussionEmptyText: { fontSize: 14 },
 
    // guide overlay
    guideOverlay: { flex: 1, backgroundColor: 'rgba(0,0,0,0.6)', justifyContent: 'center', alignItems: 'center' },