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/PostCard.jsx

@@ -8,7 +8,7 @@ import BrandBadge from './BrandBadge'
 import StatusBadge from './StatusBadge'
 import { PlatformIcons } from './PlatformIcon'
 
-export default function PostCard({ post, onClick, onMove, compact = false }) {
+export default function PostCard({ post, onClick, onMove, compact = false, checkboxSlot }) {
   const { t } = useLanguage()
   const { getBrandName } = useContext(AppContext)
   const brandName = getBrandName(post.brand_id || post.brandId) || post.brand_name || post.brand
@@ -97,6 +97,7 @@ export default function PostCard({ post, onClick, onMove, compact = false }) {
   // Table row view
   return (
     <tr onClick={onClick} className="hover:bg-surface-secondary cursor-pointer group">
+      {checkboxSlot && <td className="w-10 px-3 py-3" onClick={e => e.stopPropagation()}>{checkboxSlot}</td>}
       <td className="px-4 py-3">
         <div className="flex items-center gap-3">
           <div className="shrink-0">