feat: add admin approve/reject adoption endpoints with validation and…

[Babigdk]

Closes #22

🚀 Admin Approval & Rejection for Adoptions

📋 Overview

This PR introduces admin-controlled approval and rejection of adoption requests.

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✅ Features Implemented

1. Approve Adoption

• Endpoint: PATCH /adoption/:id/approve
• Only accessible by ADMIN
• Validates adoption is PENDING
• Updates status → APPROVED
• Returns updated adoption with relations

2. Reject Adoption

• Endpoint: PATCH /adoption/:id/reject
• Only accessible by ADMIN
• Validates adoption is PENDING
• Updates status → REJECTED
• Accepts optional rejection reason
• Uses Prisma transaction for safety

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🔒 Validation & Authorization

• ADMIN role required (JwtAuthGuard + RolesGuard)
• Prevents invalid transitions (non-PENDING)
• Returns:
  • 404 if not found
  • 400 if invalid state
  • 403 if unauthorized

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⚠️ Notes

• No schema changes were made (as required)
• approvedAt and pet status updates were not implemented due to schema limitations

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🧪 Testing

• Approval flow tested (success + failure cases)
• Rejection flow tested (with/without reason)
• Authorization checks verified

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📦 Files Changed

• adoption.controller.ts
• adoption.service.ts
• dto/reject-adoption.dto.ts

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✅ Status

Ready for review 🚀

[Babigdk]

Hi I have created a new pull request for this assigned issue kindly merge. Thanks