RM-236: Only show tickets and transcripts a user have permission

[biast12]

Description

RM-236
Introduces logic to restrict ticket and transcript visibility for users who are only members of panel-specific support teams, without guild-wide permissions. Adds utility functions to determine panel team membership and to fetch accessible panel IDs, and applies these filters in the relevant API endpoints.

Needs: TicketsBot-cloud/database#21

Type of Change

• Bug fix
• New feature
• Breaking change
• Improvement

Testing

Have a user who's only a part of 1 panel team, open 2 ticket, 1 from the panel they have access to, and one from a panel they don't have access to, in the tickets tab should they only see the one they have access to, then switch the panels and they should switch in the dashboard too, then close both tickets, and only the one they have access to when closed should be visible in the transcripts tab

Checklist

• My code follows the style of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works