[Refactor] Rename NSA → DSA: user-facing aliases, file/class/import rename (#25821)

Co-authored-by: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

docs_new/docs/hardware-platforms/plugin.mdx

@@ -512,9 +512,9 @@ python -c "from sglang.srt.platforms import current_platform; print(current_plat
       <td>MLA KV cache pool class</td>
     </tr>
     <tr>
-      <td><code>get_nsa_kv_pool_cls()</code></td>
+      <td><code>get_dsa_kv_pool_cls()</code></td>
       <td><code>raise NotImplementedError</code></td>
-      <td>NSA KV cache pool class (DeepSeek V3.2)</td>
+      <td>DSA KV cache pool class (DeepSeek V3.2)</td>
     </tr>
     <tr>
       <td><code>get_paged_allocator_cls()</code></td>