fix(mentor): show non-suspended users in pool + picker (§B/§C)

mentor.getCandidates and mentor.getMentorPool both filtered on
status='ACTIVE', which excluded every seeded mentor (status=NONE)
and any INVITED mentor. Production scenario: PR 4's Manual Picker and
PR 5's pool counts both rendered empty against real data.

Filter changed to status != SUSPENDED — admins want to see all mentors
they manage (including INVITED + NONE), but not suspended ones.

Found via Playwright smoke of PR 5: pool count read 0 against 4 seeded
mentors with roles[]=['MENTOR'], status='NONE'.

src/server/routers/mentor.ts

@@ -169,7 +169,7 @@ export const mentorRouter = router({
       const mentors = await ctx.prisma.user.findMany({
         where: {
           roles: { has: 'MENTOR' },
-          status: 'ACTIVE',
+          status: { not: 'SUSPENDED' },
         },
         select: {
           id: true,
@@ -996,7 +996,7 @@ export const mentorRouter = router({
       const mentors = await ctx.prisma.user.findMany({
         where: {
           roles: { has: 'MENTOR' },
-          status: 'ACTIVE',
+          status: { not: 'SUSPENDED' },
         },
         select: {
           id: true,