feat: add multi-role editor to member detail page

Adds an "Additional Roles" checkbox section below the primary Role
dropdown. Admins can now grant a user multiple dashboard views (e.g.,
Observer + Jury Member) without changing their primary role. The roles
array is saved alongside the primary role and used by the role switcher.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/routers/user.ts

@@ -547,6 +547,7 @@ export const userRouter = router({
         email: z.string().email().optional(),
         name: z.string().optional().nullable(),
         role: z.enum(['SUPER_ADMIN', 'PROGRAM_ADMIN', 'AWARD_MASTER', 'JURY_MEMBER', 'MENTOR', 'OBSERVER', 'APPLICANT', 'AUDIENCE']).optional(),
+        roles: z.array(z.enum(['SUPER_ADMIN', 'PROGRAM_ADMIN', 'AWARD_MASTER', 'JURY_MEMBER', 'MENTOR', 'OBSERVER', 'APPLICANT', 'AUDIENCE'])).optional(),
         status: z.enum(['NONE', 'INVITED', 'ACTIVE', 'SUSPENDED']).optional(),
         expertiseTags: z.array(z.string()).optional(),
         maxAssignments: z.number().int().min(1).max(100).optional().nullable(),