Add: Create Author UI modal in SuperAdmin panel with plan selection

app/superadmin/templates/superadmin.html

@@ -254,7 +254,8 @@
         <div class="search-bar"><span>🔍</span><input type="text" placeholder="Search authors..." id="author-search" oninput="filterAuthors()"></div>
         <div class="toolbar-spacer"></div>
         <span class="text-xs text-muted" id="author-count">— authors</span>
-        <button class="btn btn-primary btn-sm" onclick="nav('grant')">+ Grant Access</button>
+        <button class="btn btn-primary btn-sm" onclick="showCreateAuthorModal()">+ Create Author</button>
+        <button class="btn btn-secondary btn-sm" onclick="nav('grant')">🔑 Grant Access</button>
       </div>
       <div class="card" style="padding:0;"><div class="table-wrap"><table><thead><tr><th>Author</th><th>Email</th><th>Role</th><th>Status</th><th>Books</th><th>Joined</th><th>Actions</th></tr></thead><tbody id="authors-body"><tr><td colspan="7" class="text-muted" style="text-align:center;padding:40px;">Loading...</td></tr></tbody></table></div></div>
     </div>
@@ -637,6 +638,53 @@ function viewAuthorDetail(id) {
     `<button class="btn btn-secondary" onclick="closeModal()">Close</button>`);
 }
 
+/* CREATE AUTHOR */
+function showCreateAuthorModal() {
+  showModal('Create New Author',
+    `<div class="modal-sub">Register a new author account. Optionally assign a subscription plan immediately.</div>
+     <div class="form-group"><label class="form-label">Full Name</label><input type="text" class="form-input" id="ca-name" placeholder="Jane Author"></div>
+     <div class="form-group"><label class="form-label">Email</label><input type="email" class="form-input" id="ca-email" placeholder="author@example.com"></div>
+     <div class="form-group"><label class="form-label">Password</label><input type="password" class="form-input" id="ca-pass" placeholder="Min 8 chars, uppercase, digit, special char"></div>
+     <div class="grid-2">
+       <div class="form-group"><label class="form-label">Plan (optional)</label>
+         <select class="form-input" id="ca-plan">
+           <option value="">No plan — register only</option>
+           <option value="monthly">Monthly</option>
+           <option value="quarterly">Quarterly</option>
+           <option value="semi_annual">Semi-Annual</option>
+           <option value="annual">Annual</option>
+         </select>
+       </div>
+       <div class="form-group"><label class="form-label">Auto-Renew</label>
+         <select class="form-input" id="ca-renew"><option value="false">No</option><option value="true">Yes</option></select>
+       </div>
+     </div>`,
+    `<button class="btn btn-secondary" onclick="closeModal()">Cancel</button><button class="btn btn-primary" onclick="executeCreateAuthor()">Create Author</button>`);
+}
+
+async function executeCreateAuthor() {
+  const name = document.getElementById('ca-name').value.trim();
+  const email = document.getElementById('ca-email').value.trim();
+  const pass = document.getElementById('ca-pass').value;
+  const plan = document.getElementById('ca-plan').value || null;
+  const autoRenew = document.getElementById('ca-renew').value === 'true';
+
+  if (!name || !email || !pass) { toast('Please fill in all required fields', 'error'); return; }
+  if (pass.length < 8) { toast('Password must be at least 8 characters', 'error'); return; }
+
+  try {
+    const body = { email, password: pass, full_name: name };
+    if (plan) { body.plan = plan; body.auto_renew = autoRenew; }
+    const result = await apiPost('/super/authors', body);
+    closeModal();
+    let msg = `Author "${name}" created successfully`;
+    if (result.subscription) msg += ` with ${plan} plan`;
+    toast(msg, 'success');
+    loadAuthors();
+    loadOverview();
+  } catch(e) { toast(e.message || 'Failed to create author', 'error'); }
+}
+
 /* SUBSCRIPTIONS — now powered by /super/grants */
 let allGrants = [];
 async function loadSubscriptions() {