fix(mobile): flex-center pill buttons and fix learning task card layout

- learning: task-list/snippet-list use column direction (row squeeze caused
  one-char-per-line vertical text in today-task cards)
- learning/profile: fold-toggle flex-centered
- login: code-button flex-centered
- practice: transcript-toggle / bubble-action / style-chip flex-centered
- questions: filter-chip flex-centered
- sop: modal-close flex-centered with 32px hit area
- web-ai: bubble-action flex-centered

mobile-uni/src/pages/user/practice/index.vue

@@ -2763,15 +2763,19 @@ onUnload(() => {
 }
 
 .transcript-toggle {
+  display: flex;
+  align-items: center;
+  justify-content: center;
   flex-shrink: 0;
+  min-height: 28px;
   margin: 0;
-  padding: 4px 12px;
+  padding: 0 12px;
   border: none;
   border-radius: 8px;
   background: rgba(20, 24, 31, 0.06);
   color: #6b7480;
   font-size: 12px;
-  line-height: 1.5;
+  line-height: 1;
 }
 
 .bubble-actions {
@@ -2783,14 +2787,18 @@ onUnload(() => {
 }
 
 .bubble-action {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  min-height: 28px;
   margin: 0;
-  padding: 4px 12px;
+  padding: 0 12px;
   border: 1px solid #d9e4f0;
   border-radius: 999px;
   background: #ffffff;
   color: #38424e;
   font-size: 12px;
-  line-height: 1.5;
+  line-height: 1;
 }
 
 .help-ref-list {
@@ -2832,15 +2840,19 @@ onUnload(() => {
 }
 
 .style-chip-row .chip {
+  display: flex;
+  align-items: center;
+  justify-content: center;
   flex-shrink: 0;
+  min-height: 30px;
   margin: 0;
-  padding: 5px 12px;
+  padding: 0 12px;
   border: 1px solid #cddcec;
   border-radius: 999px;
   background: #ffffff;
   color: #1f5c9d;
   font-size: 13px;
-  line-height: 1.4;
+  line-height: 1;
 }
 
 .style-chip-row + .chat-composer-wrap,