Add queue bulk editing and fix milestone time display

New Features:
- Queue bulk edit: Select multiple pending items and edit printer
  assignment, print options, or cancel them at once (Issue #159)
- Tri-state toggles (unchanged/on/off) for selective field updates

Fixes:
- Progress milestone notifications showed wrong time (e.g., "17m" instead
  of "17h 47m") - fixed by converting remaining_time from minutes to
  seconds (Issue #157)
- File Manager folder names now show full name on hover tooltip (Issue #160)

Backend:
- Added PATCH /queue/bulk endpoint for bulk updates
- Route ordering fixed to prevent /bulk matching as /{item_id}

Frontend:
- Added checkbox selection to pending queue items
- Added bulk action toolbar with Select All, Edit Selected, Cancel Selected
- Created BulkEditModal with tri-state toggles for each setting

Tests:
- Added 7 integration tests for bulk update endpoint

Closes #159

frontend/src/api/client.ts

@@ -1065,6 +1065,28 @@ export interface PrintQueueItemUpdate {
   use_ams?: boolean;
 }
 
+export interface PrintQueueBulkUpdate {
+  item_ids: number[];
+  printer_id?: number | null;
+  scheduled_time?: string | null;
+  require_previous_success?: boolean;
+  auto_off_after?: boolean;
+  manual_start?: boolean;
+  // Print options
+  bed_levelling?: boolean;
+  flow_cali?: boolean;
+  vibration_cali?: boolean;
+  layer_inspect?: boolean;
+  timelapse?: boolean;
+  use_ams?: boolean;
+}
+
+export interface PrintQueueBulkUpdateResponse {
+  updated_count: number;
+  skipped_count: number;
+  message: string;
+}
+
 // MQTT Logging types
 export interface MQTTLogEntry {
   timestamp: string;
@@ -2374,6 +2396,11 @@ export const api = {
     request<{ message: string }>(`/queue/${id}/stop`, { method: 'POST' }),
   startQueueItem: (id: number) =>
     request<PrintQueueItem>(`/queue/${id}/start`, { method: 'POST' }),
+  bulkUpdateQueue: (data: PrintQueueBulkUpdate) =>
+    request<PrintQueueBulkUpdateResponse>('/queue/bulk', {
+      method: 'PATCH',
+      body: JSON.stringify(data),
+    }),
 
   // K-Profiles
   getKProfiles: (printerId: number, nozzleDiameter = '0.4') =>