feat: bulk delete, team dispatch, calendar views, timeline colors

- Multi-select bulk delete in all 5 list views (Artefacts, Posts, Tasks,
  Issues, Assets) with cascade deletes and confirmation modals
- Team-based issue dispatch: team picker on public issue form, team filter
  on Issues page, copy public link from Team page and Issues header,
  team assignment in IssueDetailPanel
- Month/Week toggle on PostCalendar and TaskCalendarView
- Month/Week/Day zoom on project and campaign timelines (InteractiveTimeline)
  and ProjectDetail GanttView, with Month as default
- Custom timeline bar colors: clickable color dot with 12-color palette
  popover on project, campaign, and task timeline bars
- Artefacts default view changed to list
- BulkSelectBar reusable component
- i18n keys for all new features (en + ar)

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

client/src/components/TaskDetailPanel.jsx

@@ -120,7 +120,7 @@ export default function TaskDetailPanel({ task, onClose, onSave, onDelete, proje
     if (!taskId) return
     try {
       const data = await api.get(`/tasks/${taskId}/attachments`)
-      setAttachments(Array.isArray(data) ? data : (data.data || []))
+      setAttachments(Array.isArray(data) ? data : [])
     } catch {
       setAttachments([])
     }