feat(auth): User Management and Access Expiry

[alexlewis9]

Summary

Enable admins to manage volunteer accounts and handle expirations.

Related Issues

• Closes User Management & Access Expiry #5

Changes

• GET /api/users – list and filter by role and activity
• PATCH /api/users/:id – update is_active and access_expires_at
• Add middleware to block expired/deactivated users

How to Test

1. Run tests: pytest users/tests.py -v

Checklist

• Tests added or updated
• CI passes (lint, tests, build)
• Documentation updated (if behavior changed)
• No secrets or credentials committed