Member directory and member management tools

## Summary
Implement a member directory and member management experience with Discord-like behavior adapted to a single guild.

## Scope
- Provide a browsable member directory with search and useful filters.
- Surface guild-local identity, including nickname/status presentation once available.
- Provide clear entry points into moderation and role-management actions for authorized staff.
- Keep ordinary members discoverable without exposing privileged controls to unauthorized users.

## Acceptance Criteria
- [ ] Users can search and browse guild members from a dedicated directory or equivalent first-class surface.
- [ ] Member entries show guild-relevant identity and presence information when available.
- [ ] Staff can open management actions from the directory without leaving the workflow.
- [ ] Unauthorized users never see or trigger privileged member-management actions.

## Operational Notes
- Large self-hosted communities need pagination or virtualization so the directory remains usable.
- Directory visibility should respect future privacy and block settings.