feat(pricing): add cucloud and bytedance payg importers

- Add import_cucloud_pricing.go for 联通云 payg 公开价抓取
- Add import_bytedance_pricing.go for 火山引擎/ByteDance Ark 定价导入
- Include test files and sample testdata for both importers
- Update plan catalog inventory docs and seeds
- Add cucloud pricing importer implementation plan
- Align pipeline scripts and smoke gate tests

scripts/testdata/cucloud_pricing_sample.html

@@ -0,0 +1,62 @@
+<section>
+  <h1>Token Plan概述</h1>
+  <table cellspacing="0">
+    <tbody>
+      <tr>
+        <td>套餐额度</td>
+        <td><p><strong>DeepSeek-V4-Pro</strong></p><p>综合单价9.30元/百万tokens</p></td>
+        <td><p><strong>DeepSeek-V4-Flash</strong></p><p>综合单价0.70元/百万tokens</p></td>
+        <td><p><strong>MiniMax-M2.5</strong></p><p>综合单价1.10元/百万tokens</p></td>
+      </tr>
+      <tr>
+        <td>25,000 credits</td>
+        <td>约 27 百万tokens</td>
+        <td>约 357 百万tokens</td>
+        <td>约 227 百万tokens</td>
+      </tr>
+    </tbody>
+  </table>
+</section>
+<section>
+  <h1>各云区域模型支持情况</h1>
+  <table cellspacing="0">
+    <tbody>
+      <tr>
+        <td>模型</td>
+        <td>呼和浩特二区</td>
+        <td>上海二十二区</td>
+        <td>武汉四区</td>
+        <td>济南五区</td>
+        <td>贵阳基地二区</td>
+      </tr>
+      <tr>
+        <td>DeepSeek-V4-Pro</td>
+        <td><br/></td>
+        <td><br/></td>
+        <td><br/></td>
+        <td><br/></td>
+        <td>支持</td>
+      </tr>
+      <tr>
+        <td>DeepSeek-V4-Flash</td>
+        <td><br/></td>
+        <td><br/></td>
+        <td><br/></td>
+        <td><br/></td>
+        <td>支持</td>
+      </tr>
+      <tr>
+        <td>MiniMax-M2.5</td>
+        <td><br/></td>
+        <td><br/></td>
+        <td>支持</td>
+        <td><br/></td>
+        <td>支持</td>
+      </tr>
+    </tbody>
+  </table>
+</section>
+<section>
+  <h1>按量计费模式</h1>
+  <p>按量计费按模型销售价实时累加，计费单位为元/千 Tokens。</p>
+</section>