feat: upgrade student vocabulary learning flow

apps/taro/src/pages/student/student.css

@@ -392,3 +392,127 @@
   word-break: break-all;
   overflow-wrap: anywhere;
 }
+
+.vocabulary-page .student-topbar {
+  margin-bottom: 20px;
+}
+
+.vocabulary-modebar {
+  margin-top: 18px;
+}
+
+.vocabulary-study {
+  display: flex;
+  flex-direction: column;
+  gap: 18px;
+}
+
+.vocabulary-progress {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+
+.vocabulary-progress-track {
+  width: 100%;
+  height: 12px;
+  overflow: hidden;
+  border-radius: 999px;
+  background: #e2e8f0;
+}
+
+.vocabulary-progress-fill {
+  height: 100%;
+  border-radius: 999px;
+  background: #2563eb;
+  transition: width 180ms ease;
+}
+
+.vocabulary-card {
+  min-height: 560px;
+  padding: 32px;
+  border: 1px solid #dbe3ee;
+  border-radius: 8px;
+  background: #fff;
+}
+
+.vocabulary-card.revealed {
+  border-color: #bfdbfe;
+  background: #f8fbff;
+}
+
+.vocabulary-word {
+  display: block;
+  margin-top: 36px;
+  color: #0f172a;
+  font-size: 64px;
+  font-weight: 850;
+  line-height: 1.05;
+  text-align: center;
+  word-break: break-word;
+}
+
+.vocabulary-phonetic {
+  display: block;
+  margin-top: 16px;
+  color: #64748b;
+  font-size: 28px;
+  line-height: 1.3;
+  text-align: center;
+}
+
+.vocabulary-card-actions {
+  justify-content: center;
+  margin-top: 26px;
+}
+
+.vocabulary-answer {
+  margin-top: 34px;
+  padding: 24px;
+  border: 1px solid #e2e8f0;
+  border-radius: 8px;
+  background: #fff;
+}
+
+.vocabulary-actions {
+  justify-content: center;
+}
+
+.vocabulary-word-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 12px;
+}
+
+.vocabulary-word-chip {
+  min-width: 0;
+  padding: 18px;
+  border: 1px solid #e2e8f0;
+  border-radius: 8px;
+  background: #fff;
+}
+
+.vocabulary-word-chip.active {
+  border-color: #2563eb;
+  background: #eff6ff;
+}
+
+.vocabulary-word-chip.favorite {
+  border-color: #f59e0b;
+}
+
+.vocabulary-chip-word {
+  display: block;
+  color: #0f172a;
+  font-size: 24px;
+  font-weight: 820;
+  line-height: 1.3;
+  word-break: break-word;
+}
+
+.vocabulary-chip-meta {
+  display: block;
+  margin-top: 6px;
+  color: #94a3b8;
+  font-size: 20px;
+}