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/components/hermes/chat/SessionListItem.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { NPopconfirm } from 'naive-ui'
+import { NPopconfirm, NCheckbox } from 'naive-ui'
 import { useI18n } from 'vue-i18n'
 import type { Session } from '@/stores/hermes/chat'
 import { formatTimestampMs } from '@/shared/session-display'
@@ -10,12 +10,15 @@ const props = defineProps<{
   pinned: boolean
   canDelete: boolean
   streaming?: boolean
+  selectable?: boolean
+  selected?: boolean
 }>()
 
 const emit = defineEmits<{
   select: []
   contextmenu: [event: MouseEvent]
   delete: []
+  'toggle-select': []
 }>()
 
 const { t } = useI18n()
@@ -24,11 +27,14 @@ const { t } = useI18n()
 <template>
   <button
     class="session-item"
-    :class="{ active }"
+    :class="{ active, 'batch-mode': selectable }"
     :aria-current="active ? 'page' : undefined"
     @click="emit('select')"
     @contextmenu="emit('contextmenu', $event)"
   >
+    <div v-if="selectable" class="session-item-checkbox">
+      <NCheckbox :checked="selected" @click.stop="emit('toggle-select')" />
+    </div>
     <div class="session-item-content">
       <span class="session-item-title-row">
         <span v-if="pinned" class="session-item-pin" aria-hidden="true">
@@ -48,7 +54,7 @@ const { t } = useI18n()
         <span class="session-item-time">{{ formatTimestampMs(session.createdAt) }}</span>
       </span>
     </div>
-    <NPopconfirm v-if="canDelete" @positive-click="emit('delete')">
+    <NPopconfirm v-if="canDelete && !selectable" @positive-click="emit('delete')">
       <template #trigger>
         <button class="session-item-delete" @click.stop>
           <svg width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><line x1="18" y1="6" x2="6" y2="18"/><line x1="6" y1="6" x2="18" y2="18"/></svg>