StatsController previously injected PersonRepository and DocumentRepository
directly, violating the controller→service→repository layering rule. Move the
two count() calls into a thin StatsService that delegates to PersonService.count
and DocumentService.count. While here, add the missing @RequirePermission(READ_ALL)
flagged by AUDIT-2 §7 — anonymous callers were able to read aggregate document/
person counts.
Refs #417 (C6.1 violation #1).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>