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/(applicant)/applicant/page.tsx

@@ -124,17 +124,17 @@ export default function ApplicantDashboardPage() {
       {/* Header */}
       <div className="flex items-start justify-between flex-wrap gap-4">
         <div className="flex items-center gap-4">
-          {/* Project logo — clickable for team leads to change */}
-          {project.isTeamLead ? (
-            <ProjectLogoUpload
-              projectId={project.id}
-              currentLogoUrl={data.logoUrl}
-              onUploadComplete={() => utils.applicant.getMyDashboard.invalidate()}
+          {/* Project logo — clickable for any team member to change */}
+          <ProjectLogoUpload
+            projectId={project.id}
+            currentLogoUrl={data.logoUrl}
+            onUploadComplete={() => utils.applicant.getMyDashboard.invalidate()}
+          >
+            <button
+              type="button"
+              className="group relative shrink-0 flex flex-col items-center gap-1 cursor-pointer"
             >
-              <button
-                type="button"
-                className="group relative shrink-0 h-14 w-14 rounded-xl border bg-muted/50 flex items-center justify-center overflow-hidden cursor-pointer hover:ring-2 hover:ring-primary/30 transition-all"
-              >
+              <div className="relative h-14 w-14 rounded-xl border bg-muted/50 flex items-center justify-center overflow-hidden hover:ring-2 hover:ring-primary/30 transition-all">
                 {data.logoUrl ? (
                   <img src={data.logoUrl} alt={project.title} className="h-full w-full object-cover" />
                 ) : (
@@ -143,17 +143,12 @@ export default function ApplicantDashboardPage() {
                 <div className="absolute inset-0 bg-black/0 group-hover:bg-black/40 transition-colors flex items-center justify-center">
                   <Pencil className="h-4 w-4 text-white opacity-0 group-hover:opacity-100 transition-opacity" />
                 </div>
-              </button>
-            </ProjectLogoUpload>
-          ) : (
-            <div className="shrink-0 h-14 w-14 rounded-xl border bg-muted/50 flex items-center justify-center overflow-hidden">
-              {data.logoUrl ? (
-                <img src={data.logoUrl} alt={project.title} className="h-full w-full object-cover" />
-              ) : (
-                <FileText className="h-7 w-7 text-muted-foreground/60" />
-              )}
-            </div>
-          )}
+              </div>
+              <span className="text-[10px] text-primary/70 group-hover:text-primary transition-colors">
+                {data.logoUrl ? 'Change' : 'Add logo'}
+              </span>
+            </button>
+          </ProjectLogoUpload>
           <div>
             <div className="flex items-center gap-3">
               <h1 className="text-2xl font-semibold tracking-tight">{project.title}</h1>