Add file requirements per round and super admin promotion via UI

Part A: File Requirements per Round
- New FileRequirement model with name, description, accepted MIME types, max size, required flag, sort order
- Added requirementId FK to ProjectFile for linking uploads to requirements
- Backend CRUD (create/update/delete/reorder) in file router with audit logging
- Mime type validation and team member upload authorization in applicant router
- Admin UI: FileRequirementsEditor component in round edit page
- Applicant UI: RequirementUploadSlot/List components in submission detail and team pages
- Viewer UI: RequirementChecklist with fulfillment status in file-viewer

Part B: Super Admin Promotion
- Added SUPER_ADMIN to role enums in user create/update/bulkCreate with guards
- Member detail page: SUPER_ADMIN dropdown option with AlertDialog confirmation
- Invite page: SUPER_ADMIN option visible only to super admins

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

prisma/schema.prisma

@@ -452,6 +452,7 @@ model Round {
   taggingJobs       TaggingJob[]
   reminderLogs      ReminderLog[]
   projectFiles      ProjectFile[]
+  fileRequirements  FileRequirement[]
   evaluationDiscussions EvaluationDiscussion[]
   messages              Message[]
 
@@ -581,10 +582,31 @@ model Project {
   @@index([country])
 }
 
+model FileRequirement {
+  id               String   @id @default(cuid())
+  roundId          String
+  name             String
+  description      String?
+  acceptedMimeTypes String[] // e.g. ["application/pdf", "video/*"]
+  maxSizeMB        Int?     // Max file size in MB
+  isRequired       Boolean  @default(true)
+  sortOrder        Int      @default(0)
+
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  // Relations
+  round Round          @relation(fields: [roundId], references: [id], onDelete: Cascade)
+  files ProjectFile[]
+
+  @@index([roundId])
+}
+
 model ProjectFile {
-  id        String   @id @default(cuid())
-  projectId String
-  roundId   String?  // Which round this file was submitted for
+  id            String   @id @default(cuid())
+  projectId     String
+  roundId       String?  // Which round this file was submitted for
+  requirementId String?  // FK to FileRequirement (if uploaded against a requirement)
 
   // File info
   fileType  FileType
@@ -605,16 +627,18 @@ model ProjectFile {
   createdAt DateTime @default(now())
 
   // Relations
-  project    Project      @relation(fields: [projectId], references: [id], onDelete: Cascade)
-  round      Round?       @relation(fields: [roundId], references: [id])
-  replacedBy ProjectFile? @relation("FileVersions", fields: [replacedById], references: [id], onDelete: SetNull)
-  replacements ProjectFile[] @relation("FileVersions")
+  project     Project          @relation(fields: [projectId], references: [id], onDelete: Cascade)
+  round       Round?           @relation(fields: [roundId], references: [id])
+  requirement FileRequirement? @relation(fields: [requirementId], references: [id], onDelete: SetNull)
+  replacedBy  ProjectFile?     @relation("FileVersions", fields: [replacedById], references: [id], onDelete: SetNull)
+  replacements ProjectFile[]   @relation("FileVersions")
 
   @@unique([bucket, objectKey])
   @@index([projectId])
   @@index([roundId])
   @@index([projectId, roundId])
   @@index([fileType])
+  @@index([requirementId])
 }
 
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