feat(vendors): add pagination and limit validation to GET/vendors

[GoluScriptMage]

🔗 Related Issue

Closes #78                                                                  
                                                                            
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## 🔖 Title
feat(vendors): add pagination and limit validation to GET /vendors          

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## 📝 Description
Adds query-based pagination (`page` and `limit`) to the `GET /vendors`      

endpoint. This prevents performance degradation when the table grows to
hundreds of vendors by replacing the full table scan with scoped database
ranges.

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## 🔄 Changes Made
- [x] Created `VendorListQueryDto` to validate query parameters (default    

page=1, limit=20, max limit=100).
- [x] Created VendorListResponseDto to format responses with standard
pagination metadata.
- [x] Updated VendorsService.getAll to map ranges (.range(offset, offset + limit - 1)) and retrieve total count from Supabase.
- [x] Updated VendorsController.list to bind query decorators and generate
Swagger documentation.

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## 📸 Screenshots (if applicable)
*N/A (Backend API changes only)*

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## 🗒️ Additional Notes
- Verified backend compilation locally using `npm run build` (build         

completes with zero errors).

[Copilot]

Pull request overview

Adds query-parameter pagination to the GET /vendors endpoint to avoid returning the full vendors table as it grows, and standardizes the response to include pagination metadata (including total count).

Changes:

• Introduces page/limit query validation via VendorListQueryDto (default page=1, limit=20; max limit=100).
• Updates VendorsService.getAll to fetch a scoped range and return total count using Supabase count: 'exact'.
• Updates GET /vendors controller route and Swagger metadata to reflect the paginated response shape.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/modules/vendors/vendors.service.ts	Implements offset/limit paging via Supabase .range(...) and returns a paginated response envelope.
src/modules/vendors/vendors.controller.ts	Binds query DTO for pagination inputs and updates Swagger response contract.
src/modules/vendors/dto/vendor-list-response.dto.ts	Adds a paginated list response DTO (data + pagination meta + message).
src/modules/vendors/dto/vendor-list-query.dto.ts	Adds validation/transforms for type, page, and limit query parameters.

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