style: 放大章节阅读区与编辑区，使其随窗口宽度自适应

阅读区：正文列上限由固定 820px 改为 min(1040px, 92vw)；打开查词面板时的容器由 1120px 改为
min(1240px, 96vw)，大屏上正文列不再比不开面板时更窄。编辑区：章节编辑对话框由固定 620px 改为
min(1180px, 94vw)，正文输入框最小高度改为 62vh（行数仅作初始值），书籍对话框 460px 改为 560px。

新增验证：reading 用例检查 768/1024/1280 三档宽度不横向溢出，并在 1280 下断言正文列宽 > 820px；
edit 用例断言章节对话框宽 > 900px、正文输入框高 > 400px 且不溢出。手机（≤760px）的底部抽屉样式未改动。

测试：学习端 159 单测、26 项 e2e、vue-tsc、build 全部通过。无长期文档影响（仅样式数值）。

learner/e2e/edit.spec.ts

@@ -80,9 +80,20 @@ test('rename the book, edit a chapter into a new version and delete both', async
   await expect(page.getByRole('heading', { name: 'A long step' })).toBeVisible()
 
   // Edit the chapter text: the new version re-processes and later becomes ready again.
+  // The chapter editor is the main writing surface, so on a wide window it must use that width and
+  // a tall body instead of a fixed 620px box.
+  await page.setViewportSize({ width: 1280, height: 900 })
   await page.getByTestId('edit-chapter-9').click()
+  await expectModalOverlay(page, page.getByTestId('chapter-dialog'))
   await expect(page.getByLabel('章节标题', { exact: true })).toHaveValue('First chapter')
   await expect(page.getByLabel('正文', { exact: true })).toHaveValue(firstText)
+  const dialog = await page.getByTestId('chapter-dialog').boundingBox()
+  expect(dialog!.width, 'the chapter editor follows the window').toBeGreaterThan(900)
+  const body = await page.getByLabel('正文', { exact: true }).boundingBox()
+  expect(body!.height, 'the text area is tall enough to write in').toBeGreaterThan(400)
+  const noOverflow = await page.evaluate(() => ({ scroll: document.documentElement.scrollWidth, inner: window.innerWidth }))
+  expect(noOverflow.scroll, 'the wide editor must not overflow').toBeLessThanOrEqual(noOverflow.inner)
+  await page.setViewportSize({ width: 1280, height: 900 })
   await page.getByLabel('正文', { exact: true }).fill('A replacement body.\n')
   await page.getByTestId('save-chapter').click()
   await expect(page.getByTestId('book-notice')).toContainText('已保存为新版本，正在重新处理')

learner/e2e/reading.spec.ts

@@ -137,6 +137,18 @@ test('paste English text, watch a chapter finish processing, then read it verbat
   await expect(page.locator('.lookup-panel')).toContainText('Princeton WordNet')
   expect(await readerText.evaluate(element => element.textContent)).toBe(pasted)
 
+  // The reading and editing surfaces must grow with the window instead of staying at a fixed
+  // 820px column, and no intermediate width may overflow sideways (the blind spot before this).
+  for (const width of [768, 1024, 1280]) {
+    await page.setViewportSize({ width, height: 900 })
+    await page.waitForTimeout(60)
+    const overflow = await page.evaluate(() => ({ scroll: document.documentElement.scrollWidth, inner: window.innerWidth }))
+    expect(overflow.scroll, `reader must not overflow at ${width}px`).toBeLessThanOrEqual(overflow.inner)
+  }
+  await page.setViewportSize({ width: 1280, height: 900 })
+  await page.waitForTimeout(60)
+  const wideBody = await page.locator('.reader-body').boundingBox()
+  expect(wideBody!.width, 'the text column follows the window').toBeGreaterThan(820)
   // Browser narrow viewport check only; this is not real-device acceptance.
   await page.setViewportSize({ width: 390, height: 844 })
   await word.click()

learner/src/style.css

@@ -227,12 +227,12 @@ h1 { font-size: 30px; font-weight: 600; margin: 14px 0; letter-spacing: 1px; }
 a.chapter-name:hover { color: var(--accent); text-decoration: underline; }
 .chapter-meta { margin: 4px 0 0; color: var(--text-muted); font-size: 13px; overflow-wrap: anywhere; }
 /* Reader keeps the pasted text exactly as it was, including line breaks and tabs. */
-.reader-page { max-width: 820px; }
+.reader-page { max-width: min(1040px, 92vw); }
 .chapter-author { margin: -6px 0 0; color: var(--text-muted); font-size: 14px; }
 .reader-text { white-space: pre-wrap; overflow-wrap: break-word; margin: 26px 0 0; font-family: Georgia, 'Times New Roman', 'Microsoft YaHei', serif; font-size: calc(17px * var(--reader-font-scale)); line-height: 2; }
 .processing-hint { padding: 36px 0; color: var(--text-muted); }
 .reader-nav { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; margin-top: 36px; padding-top: 22px; border-top: 1px solid var(--border); }
-.reader-page.has-lookup { max-width: 1120px; }
+.reader-page.has-lookup { max-width: min(1240px, 96vw); }
 .reader-workspace { display: grid; grid-template-columns: minmax(0, 1fr); gap: 32px; align-items: start; }
 .has-lookup .reader-workspace { grid-template-columns: minmax(0, 1fr) 320px; }
 .reader-body { min-width: 0; }
@@ -270,6 +270,9 @@ a.chapter-name:hover { color: var(--accent); text-decoration: underline; }
 .lookup-term .el-radio-group { margin-top: 8px; flex-wrap: wrap; gap: 4px 12px; }
 .lookup-term .el-textarea { margin-top: 8px; }
 .lookup-term .el-textarea textarea { font: inherit; line-height: 1.6; }
+/* The chapter body is the main editing surface, so it grows with the window instead of staying
+   fixed at its rows attribute; the dialog is sized by viewport so a small laptop still fits. */
+.chapter-text-input .el-textarea__inner { min-height: 62vh; line-height: 1.9; }
 .lookup-saved { color: var(--saved); font-size: 14px; margin: 12px 0 0; }
 .lookup-actions { display: flex; gap: 8px; margin-top: 14px; flex-wrap: wrap; }
 .review-page { max-width: 680px; }

learner/src/views/BookView.vue

@@ -398,7 +398,7 @@ onUnmounted(() => library.closeBook())
         </section>
       </template>
 
-      <ElDialog v-model="bookDialog" title="编辑书籍" width="460" data-testid="book-dialog">
+      <ElDialog v-model="bookDialog" title="编辑书籍" width="560" data-testid="book-dialog">
         <div class="field-row">
           <label for="book-title">书名</label>
           <ElInput id="book-title" v-model="bookTitle" type="text" maxlength="200" :disabled="saving" />
@@ -414,7 +414,7 @@ onUnmounted(() => library.closeBook())
         </template>
       </ElDialog>
 
-      <ElDialog v-model="chapterDialog" title="编辑章节" width="620" data-testid="chapter-dialog">
+      <ElDialog v-model="chapterDialog" title="编辑章节" width="min(1180px, 94vw)" data-testid="chapter-dialog">
         <p v-if="chapterLoading" role="status" class="loading">正在加载…</p>
         <template v-else-if="chapterSource">
           <div class="field-row">
@@ -426,7 +426,7 @@ onUnmounted(() => library.closeBook())
             <ElInput id="chapter-author" v-model="chapterAuthor" type="text" maxlength="120" placeholder="可留空" :disabled="saving" data-testid="chapter-author" />
           </div>
           <label for="chapter-text">正文</label>
-          <ElInput id="chapter-text" v-model="chapterText" type="textarea" :rows="18" :disabled="saving" />
+          <ElInput id="chapter-text" v-model="chapterText" type="textarea" class="chapter-text-input" :rows="18" :disabled="saving" />
           <p class="counter">{{ chapterLength }} / {{ TEXT_MAX_CODE_POINTS }} 字符 · 保存后重新处理这一章</p>
 
           <div class="attachment-block">