feat(i18n): the tile grid in Chinese (zh-CN)

Owner request: with App Settings language set to 简体中文, the grid reads
fully in Chinese. Every string the grid puts on screen gets its own
ZH_CN entry, so none reaches the generic leading-verb fallback: the Tiles
button (both states, with the right-click hint), the Tiles and Split
chips, the grid region, the Help modal's Tiles rows, the shortcut
registry's Tiles group and labels (overlay and App Settings list, and
"not bound"), "Open group as tiles", the picker, a tile's +, the header
buttons, the Attach overlay (not attached, attaching, exited, ended, the
hint), the empty slot, the dividers, the Split button while tiles are
open, and the toasts. Strings with a count, an exit code or a duration
are translateDynamic patterns: the cap texts (both wordings, with and
without ": the new session opens on its own"), "This window fits N
tile(s)", the auto-zoom hint, "The agent exited (N)" / "(signal N)", the
crash-restart confirm (the existing confirm wrapper runs it through t();
the session name passes through untranslated, in the single view too),
and the tile header tooltip ("idle 3m"), which requires the duration so
bare state words stay out of the table (they collide with other
surfaces, see mobile-overview.js).

Wording: 平铺 for the feature, 窗格 for one tile, 附加 for attach, 智能体,
案例, as the table already has them. Key names stay; Click, Right-click
(mouse actions) and Arrows in the Help modal's key column are translated.
English reads exactly as before (only additions to the table).

test/tile-grid-i18n.test.ts drives the real tile code through every
state that writes text, harvests each string and requires Chinese with
no Latin word left beyond key names and durations, and the same English
in en; plus the markup through the real translator in JSDOM, and session
and group names (also when they equal a UI word) staying untranslated.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/web/public/i18n.js

@@ -96,6 +96,56 @@
     'Split: close the second session': '分屏：关闭第二个会话',
     'Close split': '关闭分屏',
     'No other sessions to split with': '没有其他可用于分屏的会话',
+    // Tile grid (tile-grid.js, docs/tile-grid-plan.md). 平铺 is the feature (the
+    // button, the setting, the grid), 窗格 one tile in it. Key names stay as
+    // they are; Click / Right-click are mouse actions, Arrows the arrow keys.
+    // Counts, exit codes and durations are patterns in translateDynamic.
+    Tiles: '平铺',
+    Split: '分屏',
+    'Tiled sessions': '平铺的会话',
+    'Tiles: show several sessions side by side (right-click to choose which)':
+      '平铺：并排显示多个会话（右键单击可选择会话）',
+    'Tiles: back to a single session (right-click to choose which sessions)':
+      '平铺：返回单个会话（右键单击可选择会话）',
+    'Split: unavailable while tiles are open': '分屏：平铺打开时不可用',
+    'Toggle Tile Grid': '切换平铺网格',
+    'Focus Tile Left': '聚焦左侧窗格',
+    'Focus Tile Right': '聚焦右侧窗格',
+    'Focus Tile Up': '聚焦上方窗格',
+    'Focus Tile Down': '聚焦下方窗格',
+    'Focus Tile Left / Right / Up / Down': '聚焦左侧 / 右侧 / 上方 / 下方窗格',
+    'Zoom Focused Tile': '放大聚焦的窗格',
+    'Remove Focused Tile': '移除聚焦的窗格',
+    'Add the Session to the Tile Grid': '将该会话加入平铺网格',
+    'Choose Which Sessions to Tile': '选择要平铺的会话',
+    'a tab': '标签页',
+    'the Tiles button': '平铺按钮',
+    Click: '单击',
+    'Right-click': '右键单击',
+    Arrows: '方向键',
+    'not bound': '未绑定',
+    'Open group as tiles': '以平铺方式打开分组',
+    'Show sessions as tiles': '以平铺方式显示会话',
+    'Open tiles': '打开平铺',
+    'No sessions to show as tiles': '没有可平铺显示的会话',
+    'This group has no session to show as tiles': '此分组没有可平铺显示的会话',
+    'Add a session to the grid': '向平铺网格添加会话',
+    'Every open session is already tiled': '所有打开的会话都已平铺',
+    'New session in this case': '在此案例中新建会话',
+    'This session is not in a case': '此会话不属于任何案例',
+    'Zoom this tile': '放大此窗格',
+    'Restore the grid': '恢复平铺网格',
+    'Remove tile (the session keeps running)': '移除窗格（会话继续运行）',
+    'Drop a tab here': '将标签页拖放到此处',
+    'Resize tile columns': '调整窗格列宽',
+    'Resize tile rows': '调整窗格行高',
+    Attach: '附加',
+    'Attaching…': '正在附加…',
+    'Not attached': '未附加',
+    'The session ended': '会话已结束',
+    'The agent exited': '智能体已退出',
+    'It cannot be restarted in place: close it from ⋯ (Close session).': '无法原地重启：请通过 ⋯（关闭会话）关闭它。',
+    'Could not attach the session': '无法附加会话',
     'Ultracode / Workflow agents': 'Ultracode / Workflow 智能体',
     'Open ultracode workflow agents': '打开 Ultracode 工作流智能体',
     Notifications: '通知',
@@ -975,6 +1025,41 @@
         /^Delete group "(.+)"\? Its tabs move to Ungrouped\.$/,
         (_m, group) => `删除分组“${group}”？其中的标签将移到未分组。`,
       ],
+      // Tile grid: counts, exit codes and durations pass through.
+      [/^Up to (\d+) tiles$/, (_m, n) => `最多 ${n} 个窗格`],
+      [/^This window fits (\d+) tiles?$/, (_m, n) => `此窗口可容纳 ${n} 个窗格`],
+      [/^The grid holds at most (\d+) tiles$/, (_m, n) => `平铺网格最多容纳 ${n} 个窗格`],
+      [
+        /^The grid already holds what this window fits \((\d+)\)$/,
+        (_m, n) => `平铺网格已达到此窗口可容纳的数量（${n}）`,
+      ],
+      [
+        /^The grid holds at most (\d+) tiles: the new session opens on its own$/,
+        (_m, n) => `平铺网格最多容纳 ${n} 个窗格：新会话将单独打开`,
+      ],
+      [
+        /^The grid already holds what this window fits \((\d+)\): the new session opens on its own$/,
+        (_m, n) => `平铺网格已达到此窗口可容纳的数量（${n}）：新会话将单独打开`,
+      ],
+      [
+        /^The window is too small for (\d+) tiles: showing the focused one$/,
+        (_m, n) => `窗口太小，容纳不下 ${n} 个窗格：只显示聚焦的窗格`,
+      ],
+      [/^The agent exited \((-?\d+)\)$/, (_m, code) => `智能体已退出（${code}）`],
+      [/^The agent exited \(signal (\d+)\)$/, (_m, signal) => `智能体已退出（信号 ${signal}）`],
+      // A session name is user text: it passes through untranslated.
+      [
+        /^(.+) was stopped after crashing repeatedly\. Restart it\?$/,
+        (_m, name) => `${name} 因反复崩溃已被停止。要重启吗？`,
+      ],
+      // A tile header's tooltip: a state and how long ("idle 3m"). The duration
+      // is required: bare state words stay out of the table, they collide with
+      // state strings on other surfaces (see mobile-overview.js).
+      [
+        /^(needs you|error|waiting|working|idle|done|exited) (<1m|\d+[dhm](?: \d+[hm])?)$/,
+        (_m, state, duration) =>
+          `${{ 'needs you': '需要你', error: '错误', waiting: '等待中', working: '工作中', idle: '空闲', done: '已完成', exited: '已退出' }[state]} ${duration}`,
+      ],
     ];
     for (const [pattern, replacement] of patterns) {
       const match = source.match(pattern);