Implement Administration & Moderation API

[RemmyAcee]

Close: #281

BE-015 Implementation is complete. Here's a summary:
Files Created (31 files)
Entities (3)

• src/admin/entities/admin.entity.ts — Admin entity with AdminRole enum (super_admin, administrator, moderator, security_analyst, governance_operator, auditor) and role hierarchy
• src/admin/entities/incident.entity.ts — Incident entity with classification, severity, status, investigation notes, resolution, and post-incident report
• src/admin/entities/moderation-report.entity.ts — ModerationReport entity with type, priority, status, evidence, and resolution
  RBAC System (5)
• src/admin/guards/admin.guard.ts — Validates JWT user is an active admin, attaches admin to request
• src/admin/guards/roles.guard.ts — Enforces role hierarchy (super_admin > admin > moderator > auditor)
• src/admin/decorators/roles.decorator.ts — @roles() decorator for endpoint-level RBAC
• src/admin/decorators/current-admin.decorator.ts — @CurrentAdmin() parameter decorator
• src/admin/decorators/permissions.decorator.ts — @permissions() fine-grained decorator
  DTOs (4 files)
• src/admin/dto/admin.dto.ts — CreateAdminDto, UpdateAdminRoleDto, UpdateAdminStatusDto, AdminLoginDto
• src/admin/dto/incident.dto.ts — CreateIncidentDto, UpdateIncidentDto, AddInvestigationNoteDto, ResolveIncidentDto, PostIncidentReportDto, IncidentQueryDto
• src/admin/dto/moderation.dto.ts — CreateReportDto, UpdateReportDto, ResolveReportDto, AssignDto, ModerationQueryDto
• src/admin/dto/dashboard.dto.ts — HealthStatusDto, DashboardOverviewDto, ModerationStatsDto, IncidentStatsDto, MonitoringMetricsDto, PaginatedResponseDto
  Services & Controllers (8 files)
• Admin Authentication & Management: admin.service.ts, admin.controller.ts
• POST /admin/auth/login, GET /admin/auth/profile
• POST/GET /admin/admins, PATCH .../role, PATCH .../status
• Moderation Queue: moderation/moderation.service.ts, moderation/moderation.controller.ts
• GET/PATCH /admin/moderation/queue, POST/GET/PATCH /admin/moderation/reports
• POST .../assign, POST .../resolve, GET /admin/moderation/stats
• Incident Management: incidents/incident.service.ts, incidents/incident.controller.ts
• POST/GET/PATCH /admin/incidents, POST .../assign, POST .../notes
• POST .../resolve, POST .../report, GET .../stats/summary
• Dashboard & Monitoring: dashboard/dashboard.service.ts, dashboard/dashboard.controller.ts
• GET /admin/dashboard/overview, health, moderation, incidents, audit, monitoring
  Module & Registration
• src/admin/admin.module.ts — Registers all components with TypeORM
• src/admin/index.ts — Barrel exports
• src/app.module.ts — Added AdminModule import
  Tests (6 files)
• 4 unit test files in src/admin/tests/: admin.service.spec.ts, admin.guard.spec.ts, roles.guard.spec.ts, moderation.service.spec.ts, incident.service.spec.ts
• 1 E2E test: test/admin.e2e-spec.ts
  Key Design Decisions
• LBAC via Role Hierarchy: Uses AdminRoleHierarchy map where super_admin (100) > auditor (30), so higher roles inherit lower role permissions
• Dual auth: AdminGuard validates the JWT user is an admin; RolesGuard enforces minimum role level
• Audit integration: All actions are logged via the existing AuditTrailService with admin metadata
• Existing convention patterns: TypeORM entities, NestJS module structure, class-validator DTOs, Swagger decorators — all consistent with the codebase

[RemmyAcee]

Done, Close #322