Expose moderation workflow tools as MCP actions

[DmyMi]

Description

Expose moderation actions through MCP so authorized moderators can review content and apply bounded actions.

MCP tools

• admin_list_reported_content
• admin_get_report_details
• admin_hide_content
• admin_restore_content
• admin_warn_user
• admin_suspend_user
• admin_resolve_report

MCP resources

• sharebite://admin/moderation-policy
• sharebite://admin/moderation-actions
• sharebite://admin/report-statuses

Acceptance criteria

• Moderator can list and inspect reported content.
• Write actions require explicit reason.
• High-impact actions, such as suspension, require confirmation.
• All actions are audit logged.
• Unauthorized users cannot access moderation tools.
• Tests cover hide, restore, warn, suspend, resolve, and invalid transition.