chore: 版本号更新至 3.2.6

- package.json version → 3.2.6
- index.html app-version → v3.2.6
- README badge、安装包名、git checkout 分支
- CHANGELOG 新增 v3.2.6 条目，更新标签链
- BUILD.md 新增 v3.2.6 构建日志，更新 checkout 命令
- DEVELOPMENT.md 补充 flex 子元素说明

src/renderer/index.html

@@ -27,7 +27,7 @@
         <div class="header-left">
             <span class="logo">🦙</span>
             <span class="app-title">Metona Ollama</span>
-            <span class="app-version">v3.2.5</span>
+            <span class="app-version">v3.2.6</span>
             <button class="icon-btn help-btn" id="btnHelp" title="使用帮助">
                 <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
                     <circle cx="12" cy="12" r="10"/><path d="M9.09 9a3 3 0 0 1 5.83 1c0 2-3 3-3 3"/>