refactor: move PipelineItems from Zustand to Provider→Service→React Query

PipelineItems are domain data and must not live in Zustand. Moves the
full stack to the correct layer: MockupPipelineProvider (localStorage
persistence + seed fallback) → pipelineService → usePipeline hooks
(useQuery for reads, useMutation for writes with cache invalidation).

pipelineStore is now UI-only: dialogOpen, pendingItem, openSavedDialog,
closeSavedDialog. All consumers updated to use the new hooks.

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

src/components/compare/CompareColumnHeader.tsx

@@ -1,6 +1,7 @@
 import { Box, Button, Chip, IconButton, Tooltip, Typography } from '@mui/material'
 import { X, AlertTriangle, BookmarkCheck, ExternalLink, Kanban } from 'lucide-react'
 import { useNavigate } from 'react-router'
+import { usePipelineItems } from '../../hooks/usePipeline'
 import { usePipelineStore } from '../../stores/pipelineStore'
 import type { UnifiedMatchResult } from '../../domain/unifiedResult'
 
@@ -20,7 +21,8 @@ interface Props {
 
 export function CompareColumnHeader({ item, onRemove }: Props) {
   const navigate = useNavigate()
-  const { items: pipelineItems, openSavedDialog } = usePipelineStore()
+  const { data: pipelineItems = [] } = usePipelineItems()
+  const { openSavedDialog } = usePipelineStore()
 
   const meta = TYPE_META[item.resultType] ?? { label: item.resultType, color: '#64748b' }
   const prop = item.resultType !== 'FUTURE_AVAILABILITY' ? (item as any).property : null