FAC-121 feat: add ProgramFilterOptionResponseDto with moodleCategoryId

[y4nder]

Summary

Create a standalone ProgramFilterOptionResponseDto that includes moodleCategoryId in the program filter response. This enables the admin frontend's Seed Users tab to derive the Moodle category for course fetching via cascading dropdowns (Semester > Department > Program).

Changes

• NEW src/modules/admin/dto/responses/program-filter-option.response.dto.ts — standalone flat DTO with own Swagger decorators and MapProgram() static mapper (follows SemesterFilterResponseDto pattern)
• MODIFIED src/modules/admin/services/admin-filters.service.ts — GetPrograms() returns ProgramFilterOptionResponseDto[]
• MODIFIED src/modules/admin/admin-filters.controller.ts — return type + @ApiResponse updated
• MODIFIED src/modules/admin/admin-filters.controller.spec.ts — mock includes moodleCategoryId
• NEW src/modules/admin/services/admin-filters.service.spec.ts — service-level test verifying MapProgram() mapping and class instance

Context

Part of the Enhance Seed Users Provision UX initiative. The admin frontend needs moodleCategoryId from the programs filter endpoint to fetch courses from the Moodle category tree API. FilterOptionResponseDto is not modified — it stays clean for campus/department consumers.

Acceptance Criteria

• GET /admin/filters/programs?departmentId=X returns moodleCategoryId: number for each program
• Swagger schema reflects the new field
• All existing tests pass, new service spec covers the mapping