Update README and tech-selection documents for clarity and accuracy

- Revised the README.md to clarify the purpose of the tech-selection documents, distinguishing between external and internal materials.
- Added a new internal document, Flutter-vs-UniApp-Speaker.md, summarizing key points from the presentation deck.
- Updated Flutter-vs-UniApp-deck.standalone.html to enhance descriptions of HarmonyOS support and installation package sizes.

tech-selection/Flutter-vs-UniApp-deck.standalone.html

@@ -389,8 +389,8 @@ table.tiny th,table.tiny td{padding:5.5px 11px;font-size:12.5px}
         <tr><td class="k">原生能力开发</td><td class="col-f">强类型代码生成，支持命令行</td><td class="col-u">原生插件已停止新增上架</td><td class="col-u">只能经 HBuilderX，不支持命令行</td></tr>
         <tr><td class="k">开源程度</td><td class="col-f mark">引擎 + 框架全开源（BSD）</td><td class="col-u">框架层开源（Apache-2.0）</td><td class="col-u">框架层开源，Runtime / SDK 闭源</td></tr>
         <tr><td class="k">大型 App 案例</td><td class="col-f">字节 90+ 款、闲鱼、美团、京东、贝壳、携程、BMW、大众安徽 ID. UNYX</td><td class="col-u">—</td><td class="col-u">未检索到同等量级公开案例</td></tr>
-        <tr><td class="k">鸿蒙</td><td class="col-u">社区分支，3.41 已发布</td><td class="col-u">支持</td><td style="color:var(--tk-success);font-weight:700">一等公民 ✓</td></tr>
-        <tr><td class="k">安装包与内存</td><td class="col-u">约多 10 MB / 35 MB</td><td class="col-u">—</td><td style="color:var(--tk-success);font-weight:700">更小 ✓</td></tr>
+        <tr><td class="k">鸿蒙</td><td class="col-u">社区分支，3.41 已发布</td><td class="col-u">支持</td><td style="color:var(--tk-success);font-weight:700">一等公民（文档用词）</td></tr>
+        <tr><td class="k">安装包与内存</td><td class="col-u">约多 10 MB / 35 MB</td><td class="col-u">—</td><td style="color:var(--tk-success);font-weight:700">体积更小</td></tr>
         <tr><td class="k">首版投入</td><td class="col-f">基准</td><td class="col-u">—</td><td class="col-u">差异在 ±10% 以内</td></tr>
       </tbody>
     </table>