Fix permission checks for tile management

[gita-agents]

Replace incorrect user permission check in cleanup_tiles_for_floor with appropriate tile-management authorization.

Findings (1)

• [MEDIUM] bug at backend/app/services/tile_service.py:191 — Incorrect permission check in cleanup_tiles_for_floor: line 191 checks user.can_manage_users() but should check user.can_manage_critical_sectors() or a tile-management-specific permission. can_manage_users() is for user administration, not tile management.
  Fix sketch: Replace can_manage_users() with an appropriate permission check for tile management, such as checking if user is admin or supervisor.

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Generated by GITA v0.1.0 onboarding agent against amass. Milestone confidence: 0.85.