Add jury assignment transfer, cap redistribution, and learning hub overhaul

- Add getTransferCandidates/transferAssignments procedures for targeted
  assignment moves between jurors with TOCTOU guards and audit logging
- Add getOverCapPreview/redistributeOverCap for auto-redistributing
  assignments when a juror's cap is lowered below their current load
- Add TransferAssignmentsDialog (2-step: select projects, pick destinations)
- Extend InlineMemberCap with over-cap detection and redistribute banner
- Extend getReassignmentHistory to show ASSIGNMENT_TRANSFER and CAP_REDISTRIBUTE events
- Learning hub: replace ResourceType/CohortLevel enums with accessJson JSONB,
  add coverImageKey, resource detail pages for jury/mentor, shared renderer
- Migration: 20260221200000_learning_hub_overhaul

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

package.json

@@ -24,14 +24,12 @@
     "@anthropic-ai/sdk": "^0.78.0",
     "@auth/prisma-adapter": "^2.7.4",
     "@blocknote/core": "^0.46.2",
-    "@blocknote/mantine": "^0.46.2",
     "@blocknote/react": "^0.46.2",
+    "@blocknote/shadcn": "^0.46.2",
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
     "@hookform/resolvers": "^3.9.1",
-    "@mantine/core": "^8.3.13",
-    "@mantine/hooks": "^8.3.13",
     "@notionhq/client": "^2.3.0",
     "@prisma/client": "^6.19.2",
     "@radix-ui/react-alert-dialog": "^1.1.4",