feat(event,guild): refactor event database lock, migrate event read flow and add guild info APIs

[pictures2333]

What changed

• improved event database lock
• Migrated event access to read_event_one / read_event_many and updated related callers.
• Added guild info APIs:
  • GET /guild/text_channels
  • GET /guild/categories
  • GET /guild/roles
• Unified guild access through shared get_guild() usage across modules.

Notes

• This PR includes API/schema response changes.
• Recommended checks: event read/lock flow, guild routes, and ctfmenu pagination behavior.