feat: Add batch delete functionality for chat sessions (#480)

* feat: add batch delete functionality for chat sessions

Backend:
- Add batchRemove controller to handle bulk session deletion
- Add POST /api/hermes/sessions/batch-delete endpoint
- Support both local session store and CLI deletion
- Return detailed results (deleted, failed, errors)

Frontend:
- Add batch selection mode with checkboxes in SessionListItem
- Add batch selection toggle and select all button
- Add batch delete button with confirmation
- Update ChatPanel to manage selected session IDs
- Add batchDeleteSessions API function

i18n:
- Add batch delete translations for all 8 languages
- Simplify "Web UI/API Server Sessions" to "Sessions"

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: vertically align buttons in session list header

Add inline-flex and center alignment to all buttons in session-list-actions
to ensure proper vertical centering with the title text.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: ensure proper vertical alignment in session list header

- Set fixed height of 22px for session-list-actions
- Add min-height and height to all buttons
- Add line-height to session-list-title for text baseline alignment
- Add min-height: 0 to session-list-header to prevent flex stretch

This ensures the title and all action buttons are perfectly vertically centered.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: call loadSessions after batch delete instead of looping deleteSession

The previous implementation was calling chatStore.deleteSession(id) in a loop
after batch delete API succeeded, which triggered individual delete API calls
for each session - causing n API requests instead of 1.

Now we simply call loadSessions() to refresh the session list from the server
after successful batch deletion, ensuring:
- Only 1 API request for batch delete
- UI stays in sync with server state
- No duplicate API calls

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor: improve update mechanism reliability

Major improvements to the update system:

**Path Resolution:**
- Remove unreliable dirname(process.execPath) assumption
- Use npm from PATH environment variable
- Dynamically get global prefix via `npm prefix -g`
- Calculate CLI path based on actual global install location

**Windows Support:**
- Remove complex cmd.exe wrapper logic
- Directly call npm.cmd (works on all Windows setups)
- Simplified quote handling

**Error Handling:**
- Add fallback error message (err.stderr || err.message || String(err))
- Add default success message when output is empty
- Wrap spawnRestart in try-finally to ensure cleanup

**Timing:**
- Increase timeout from 120s to 10min (slow network support)
- Increase restart delay from 2s to 3s (safer margin)

**Code Quality:**
- Remove unused functions (getNodeBinDir, getWindowsShell, quoteForWindowsCommand)
- Use constants instead of magic numbers (10 * 60 * 1000)
- More maintainable and cross-platform compatible

This fixes issues where updates would fail due to incorrect npm/CLI paths
on systems with non-standard Node.js installations.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/client/src/i18n/locales/zh.ts

@@ -134,8 +134,8 @@ export default {
     send: '发送',
     contextUsed: '上下文已用:',
     sessions: '会话',
-    webUiSessions: 'Web UI/API Server 会话',
-    sessionScopeHint: '这里只显示 Web UI/API Server 会话；CLI、Telegram、Discord、Cron 等通道会话在历史中只读查看。',
+    webUiSessions: '会话',
+    sessionScopeHint: '这里只显示当前会话；CLI、Telegram、Discord、Cron 等通道会话在历史中只读查看。',
     openHistory: '打开历史',
     hermesHistory: 'Hermes 历史',
     historyScopeHint: '这里按来源只读查看 Hermes 历史会话。',
@@ -153,6 +153,12 @@ export default {
     newChat: '新建对话',
     deleteSession: '确定删除此会话？',
     sessionDeleted: '会话已删除',
+    toggleBatchMode: '批量选择',
+    selectAll: '全选',
+    confirmBatchDelete: '确定删除选中的 {count} 个会话？',
+    batchDeleteSuccess: '已删除 {count} 个会话',
+    batchDeletePartial: '{failed} 个会话删除失败',
+    batchDeleteFailed: '批量删除失败',
     rename: '重命名',
     pin: '置顶',
     unpin: '取消置顶',