style: improve plugin docs title hierarchy

- h3: 18px→22px, bolder + bottom border separator
- h4: added color, bolder weight, tighter spacing

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

app/src/main/assets/console.css

@@ -950,16 +950,18 @@ body {
 
 .doc-section h3 {
     color: var(--primary-color);
-    font-size: 18px;
-    font-weight: 500;
-    margin-bottom: 12px;
+    font-size: 22px;
+    font-weight: 600;
+    margin-bottom: 16px;
+    padding-bottom: 10px;
+    border-bottom: 2px solid var(--primary-light);
 }
 
 .doc-section h4 {
-    color: var(--terminal-fg);
-    font-size: 16px;
-    font-weight: 500;
-    margin: 16px 0 8px 0;
+    color: var(--primary-dark);
+    font-size: 15px;
+    font-weight: 600;
+    margin: 18px 0 6px 0;
 }
 
 .doc-section h5 {