fix: admin role change, logo access, magic link validation, login help

- Add updateTeamMemberRole mutation for admins to change team member roles
- Allow any team member (not just lead) to change project logo
- Add visible "Add logo"/"Change" label under logo for discoverability
- Pre-check email existence before sending magic link (show error)
- Add "forgot which email" contact link on login page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/(admin)/admin/projects/[id]/page.tsx

@@ -171,6 +171,16 @@ function ProjectDetailContent({ projectId }: { projectId: string }) {
     },
   })
 
+  const updateTeamMemberRole = trpc.project.updateTeamMemberRole.useMutation({
+    onSuccess: () => {
+      toast.success('Role updated')
+      utils.project.getFullDetail.invalidate({ id: projectId })
+    },
+    onError: (err) => {
+      toast.error(err.message || 'Failed to update role')
+    },
+  })
+
   const removeTeamMember = trpc.project.removeTeamMember.useMutation({
     onSuccess: () => {
       toast.success('Team member removed')
@@ -538,9 +548,25 @@ function ProjectDetailContent({ projectId }: { projectId: string }) {
                         <Link href={`/admin/members/${member.user.id}`} className="font-medium text-sm truncate hover:underline text-primary">
                           {member.user.name || 'Unnamed'}
                         </Link>
-                        <Badge variant="outline" className="text-xs">
-                          {member.role === 'LEAD' ? 'Lead' : member.role === 'ADVISOR' ? 'Advisor' : 'Member'}
-                        </Badge>
+                        <Select
+                          value={member.role}
+                          onValueChange={(value) =>
+                            updateTeamMemberRole.mutate({
+                              projectId: project.id,
+                              userId: member.user.id,
+                              role: value as 'LEAD' | 'MEMBER' | 'ADVISOR',
+                            })
+                          }
+                        >
+                          <SelectTrigger className="h-6 w-auto text-xs px-2 py-0 border-dashed gap-1">
+                            <SelectValue />
+                          </SelectTrigger>
+                          <SelectContent>
+                            <SelectItem value="LEAD">Lead</SelectItem>
+                            <SelectItem value="MEMBER">Member</SelectItem>
+                            <SelectItem value="ADVISOR">Advisor</SelectItem>
+                          </SelectContent>
+                        </Select>
                       </div>
                       <p className="text-xs text-muted-foreground truncate">
                         {member.user.email}