fix(layout): 侧边栏置顶，文档标签栏移到侧边栏右侧

TabBar 从菜单栏下方的整行移入主区右侧内容列（新增 .content-col 纵向容器），
侧边栏自此从菜单栏下方贯通到状态栏；隐藏侧边栏时标签栏占满整行。
打印规则同步覆盖新容器。无头浏览器实测：标签栏左边缘与侧边栏右边缘对齐
（250px）。vitest 87 通过 + 2 跳过，tsc 与构建通过。

src/App.tsx

@@ -1150,19 +1150,6 @@ export default function App() {
     <div className="app">
       <TitleBar docTitle={tab?.title ?? 'new-markdown'} dirty={tab ? isDirty(tab) : false} />
       <MenuBar menus={menus} />
-      <TabBar
-        tabs={state.tabs}
-        activeId={state.activeId}
-        onActivate={(id) => { dispatch({ type: 'activate', id }); setSourceMode(false) }}
-        onClose={closeTab}
-        onCloseOthers={(id) => requestClose(state.tabs.filter((t) => t.id !== id).map((t) => t.id), () => dispatch({ type: 'closeOthers', id }))}
-        onCloseRight={(id) => {
-          const idx = state.tabs.findIndex((t) => t.id === id)
-          requestClose(state.tabs.slice(idx + 1).map((t) => t.id), () => dispatch({ type: 'closeRight', id }))
-        }}
-        onNew={newDoc}
-        onMove={(id, toIndex) => dispatch({ type: 'move', id, toIndex })}
-      />
       <div className="main">
         {ui.sidebar && (
           <div style={{ width: ui.sidebarWidth, flex: 'none', display: 'flex' }}>
@@ -1185,6 +1172,20 @@ export default function App() {
             />
           </div>
         )}
+        <div className="content-col">
+        <TabBar
+          tabs={state.tabs}
+          activeId={state.activeId}
+          onActivate={(id) => { dispatch({ type: 'activate', id }); setSourceMode(false) }}
+          onClose={closeTab}
+          onCloseOthers={(id) => requestClose(state.tabs.filter((t) => t.id !== id).map((t) => t.id), () => dispatch({ type: 'closeOthers', id }))}
+          onCloseRight={(id) => {
+            const idx = state.tabs.findIndex((t) => t.id === id)
+            requestClose(state.tabs.slice(idx + 1).map((t) => t.id), () => dispatch({ type: 'closeRight', id }))
+          }}
+          onNew={newDoc}
+          onMove={(id, toIndex) => dispatch({ type: 'move', id, toIndex })}
+        />
         <div className="editor-area" style={{ ['--doc-zoom' as string]: zoom }}>
           {!tab && (
             <div className="empty-state">
@@ -1285,6 +1286,7 @@ export default function App() {
           )}
         </div>
         </div>
+      </div>
       <StatusBar
         words={statusCounts.words}
         chars={statusCounts.chars}

src/styles.css

@@ -56,7 +56,9 @@ button { font: inherit; color: inherit; }
 .menu-divider { height: 1px; background: var(--border); margin: 5px 8px; }
 
 /* 标签栏 */
-.tabbar { display: flex; align-items: stretch; background: var(--bg-panel); border-bottom: 1px solid var(--border); min-height: 36px; overflow-x: auto; }
+.tabbar { display: flex; align-items: stretch; background: var(--bg-panel); border-bottom: 1px solid var(--border); min-height: 36px; overflow-x: auto; flex: none; }
+/* 左侧栏置顶、文档标签栏移到侧边栏右侧的内容列顶部 */
+.content-col { flex: 1; display: flex; flex-direction: column; min-width: 0; min-height: 0; }
 .tab { display: flex; align-items: center; gap: 7px; padding: 0 8px 0 14px; font-size: 13px; cursor: pointer; border-right: 1px solid var(--border); white-space: nowrap; color: var(--text-dim); }
 .tab.active { background: var(--bg-editor); color: var(--text); box-shadow: inset 0 2px 0 var(--accent); }
 .tab-title { max-width: 180px; overflow: hidden; text-overflow: ellipsis; }
@@ -95,7 +97,7 @@ button { font: inherit; color: inherit; }
 .tree-icon { color: var(--text-dim); width: 12px; flex: none; }
 
 .editor-scroll { flex: 1; overflow-y: auto; background: var(--bg-editor); min-width: 0; position: relative; }
-.editor-area { flex: 1; display: flex; min-width: 0; position: relative; }
+.editor-area { flex: 1; display: flex; min-width: 0; min-height: 0; position: relative; }
 /* 标签保活后每个窗格自带滚动容器，各自保留滚动位置；窗格加载状态覆盖层 */
 .pane-loading { position: absolute; inset: 0; display: flex; flex-direction: column; gap: 12px; align-items: center; justify-content: center; color: var(--text-dim); font-size: 13px; background: var(--doc-paper); z-index: 5; }
 .pane-spinner { width: 26px; height: 26px; border-radius: 50%; border: 3px solid var(--border); border-top-color: var(--accent); animation: pane-spin 0.8s linear infinite; }
@@ -269,7 +271,7 @@ kbd { background: var(--code-bg); border: 1px solid var(--border); border-radius
 @media print {
   .titlebar, .menubar, .tabbar, .sidebar, .statusbar, .modal-backdrop, .app-notice, .context-menu,
   .table-toolbar, .tree-context-menu, .findbar, .mermaid-head { display: none !important; }
-  .app, .main, .editor-scroll { display: block !important; height: auto !important; overflow: visible !important; }
+  .app, .main, .content-col, .editor-area, .editor-scroll { display: block !important; height: auto !important; overflow: visible !important; }
   .editor-scroll { background: #fff !important; }
   /* 打印只出活动窗格：保活的隐藏窗格不能被上面的 display:block 通杀带出来 */
   .editor-scroll.tab-pane { display: none !important; }