feature: added AdminJS as the admin panel

[hugo2006alm]

The admin Panel was added and configured for editing Users and Tickets.
Also, the User model has a new field "isAdmin", used to check if the User has access to the Admin panel.

[limwa]

Please add instructions on what needs to be done after add a new model or modifying an existing one

[limwa]

This PR doesn't build as-is. I'm getting the following error:

2025-Jan-19 19:49:56.868911
#18 58.79 app/admin/auth.ts(38,3): error TS2322: Type '({ email, password }: DefaultAuthenticatePayload) => Promise<{ email: string; id: number; } | null>' is not assignable to type '(payload: DefaultAuthenticatePayload, context?: any) => Promise<CurrentAdmin | null>'.
2025-Jan-19 19:49:56.868911
#18 58.79   Type 'Promise<{ email: string; id: number; } | null>' is not assignable to type 'Promise<CurrentAdmin | null>'.
2025-Jan-19 19:49:56.868911
#18 58.79     Type '{ email: string; id: number; } | null' is not assignable to type 'CurrentAdmin | null'.
2025-Jan-19 19:49:56.868911
#18 58.79       Type '{ email: string; id: number; }' is not assignable to type 'CurrentAdmin'.
2025-Jan-19 19:49:56.868911
#18 58.79         Types of property 'id' are incompatible.
2025-Jan-19 19:49:56.868911
#18 58.79           Type 'number' is not assignable to type 'string'.

[tomaspalma]

For reference, I've added a seeder that creates a mock admin account.

email: [email protected]
password: password