feat(ST-108/ST-208): replace inline forms with PBI and story dialogs

- PbiDialog: create/edit with priority select and optional description
- StoryDialog: create/edit with priority, description, acceptance criteria, activity log, and delete
- PrioritySelect: reusable controlled select component
- Edit icons always visible on PBI rows and story blocks
- Dialog backdrop uses 40% opacity blur

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

components/shared/priority-select.tsx

@@ -0,0 +1,43 @@
+'use client'
+
+import { Select, SelectContent, SelectItem, SelectTrigger } from '@/components/ui/select'
+import { cn } from '@/lib/utils'
+
+export const PRIORITY_LABELS: Record<number, string> = {
+  1: 'Kritiek',
+  2: 'Hoog',
+  3: 'Gemiddeld',
+  4: 'Laag',
+}
+
+export const PRIORITY_COLORS: Record<number, string> = {
+  1: 'bg-priority-critical/15 text-priority-critical border-priority-critical/30',
+  2: 'bg-priority-high/15 text-priority-high border-priority-high/30',
+  3: 'bg-priority-medium/15 text-priority-medium border-priority-medium/30',
+  4: 'bg-priority-low/15 text-priority-low border-priority-low/30',
+}
+
+interface PrioritySelectProps {
+  value: number
+  onChange: (value: number) => void
+  className?: string
+}
+
+export function PrioritySelect({ value, onChange, className }: PrioritySelectProps) {
+  return (
+    <Select
+      value={String(value)}
+      onValueChange={(v) => { if (v) onChange(parseInt(v)) }}
+    >
+      <SelectTrigger className={cn('w-full', className)}>
+        {PRIORITY_LABELS[value] ?? String(value)}
+      </SelectTrigger>
+      <SelectContent>
+        <SelectItem value="1">Kritiek</SelectItem>
+        <SelectItem value="2">Hoog</SelectItem>
+        <SelectItem value="3">Gemiddeld</SelectItem>
+        <SelectItem value="4">Laag</SelectItem>
+      </SelectContent>
+    </Select>
+  )
+}