Fix round deletion FK constraint with migration and defensive code

- Add SQL migration to CASCADE Evaluation.formId and SET NULL ProjectFile.roundId
- Explicitly delete evaluations in round delete transaction as defensive measure
- Make sidebar Apply Page link dynamic using current edition context

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

prisma/migrations/20260210000000_fix_round_delete_cascades/migration.sql

@@ -0,0 +1,13 @@
+-- Fix round deletion FK constraint errors
+-- Add CASCADE on Evaluation.formId so deleting EvaluationForm cascades to Evaluations
+-- Add SET NULL on ProjectFile.roundId so deleting Round nullifies the reference
+
+-- AlterTable: Evaluation.formId -> onDelete CASCADE
+ALTER TABLE "Evaluation" DROP CONSTRAINT "Evaluation_formId_fkey";
+ALTER TABLE "Evaluation" ADD CONSTRAINT "Evaluation_formId_fkey"
+    FOREIGN KEY ("formId") REFERENCES "EvaluationForm"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AlterTable: ProjectFile.roundId -> onDelete SET NULL
+ALTER TABLE "ProjectFile" DROP CONSTRAINT "ProjectFile_roundId_fkey";
+ALTER TABLE "ProjectFile" ADD CONSTRAINT "ProjectFile_roundId_fkey"
+    FOREIGN KEY ("roundId") REFERENCES "Round"("id") ON DELETE SET NULL ON UPDATE CASCADE;