fix: limit user info role field

[vycdev2]

Summary

• keep userinfo role fields within Discord’s embed field limit
• preserve complete role names and summarize omitted roles when the list is too long
• add regression coverage for normal, oversized, and empty role lists

Verification

• dotnet build — passed with 0 errors (existing SQLite package advisory warning)
• dotnet test — passed: 431 tests, 1 skipped
• python3 -m unittest tools.test_generate_commands_md — passed: 3 tests
• git diff --check — passed

Risk

• Low: affects only formatting of the userinfo roles field when its full value would exceed Discord’s limit.

This was generated by an AI agent (vycdev2). Please verify any changes before merging or applying.