Fix project detail 500 error and round deletion data integrity

- Add missing migration for FileRequirement table and ProjectFile.requirementId
  column (existed in Prisma schema but had no migration, causing all queries
  with `include: { files: true }` to fail with column not found)
- Make projectTags query resilient with try-catch in project.get
- Reset project status to SUBMITTED when round is deleted (prevents orphaned
  ASSIGNED status after ON DELETE SET NULL nullifies roundId)
- Fix round creation/update to allow requiredReviews=0 for filtering rounds
- Parse Zod validation errors in round creation error display

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

prisma/migrations/20260211000000_add_file_requirements/migration.sql

@@ -0,0 +1,30 @@
+-- CreateTable
+CREATE TABLE "FileRequirement" (
+    "id" TEXT NOT NULL,
+    "roundId" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "description" TEXT,
+    "acceptedMimeTypes" TEXT[],
+    "maxSizeMB" INTEGER,
+    "isRequired" BOOLEAN NOT NULL DEFAULT true,
+    "sortOrder" INTEGER NOT NULL DEFAULT 0,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "FileRequirement_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "FileRequirement_roundId_idx" ON "FileRequirement"("roundId");
+
+-- AddForeignKey
+ALTER TABLE "FileRequirement" ADD CONSTRAINT "FileRequirement_roundId_fkey" FOREIGN KEY ("roundId") REFERENCES "Round"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AlterTable: add requirementId to ProjectFile
+ALTER TABLE "ProjectFile" ADD COLUMN "requirementId" TEXT;
+
+-- CreateIndex
+CREATE INDEX "ProjectFile_requirementId_idx" ON "ProjectFile"("requirementId");
+
+-- AddForeignKey
+ALTER TABLE "ProjectFile" ADD CONSTRAINT "ProjectFile_requirementId_fkey" FOREIGN KEY ("requirementId") REFERENCES "FileRequirement"("id") ON DELETE SET NULL ON UPDATE CASCADE;