chore(rvw): Migrate review_tasks table to rvw_schema

Database migration:
- Move review_tasks table from public to rvw_schema
- Update Prisma schema @@schema directive
- Regenerate Prisma Client

Verified:
- Table location: rvw_schema
- Prisma ORM queries: working
- Data integrity: 40 records preserved
- User relation: working

Documentation updated to reflect schema migration complete.

backend/prisma/schema.prisma

@@ -337,7 +337,7 @@ model ReviewTask {
   @@index([createdAt])
   @@index([isArchived])
   @@map("review_tasks")
-  @@schema("public")
+  @@schema("rvw_schema")
 }
 
 model AslScreeningProject {