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>

prisma/migrations/20260221200000_learning_hub_overhaul/migration.sql

@@ -0,0 +1,16 @@
+-- Learning Hub Overhaul: Remove ResourceType/CohortLevel enums, add accessJson + coverImageKey
+
+-- Drop columns that reference the enums
+ALTER TABLE "LearningResource" DROP COLUMN "resourceType";
+ALTER TABLE "LearningResource" DROP COLUMN "cohortLevel";
+
+-- Drop the cohortLevel index
+DROP INDEX IF EXISTS "LearningResource_cohortLevel_idx";
+
+-- Add new columns
+ALTER TABLE "LearningResource" ADD COLUMN "accessJson" JSONB;
+ALTER TABLE "LearningResource" ADD COLUMN "coverImageKey" TEXT;
+
+-- Drop the enum types
+DROP TYPE IF EXISTS "ResourceType";
+DROP TYPE IF EXISTS "CohortLevel";