v1.6.5: fix attendance unique constraint, schema sync, seed script

- Change attendance idx_attendance_user_date from unique to index (allow multiple shifts per day)
- Reset migrations to single baseline init migration
- Add seed script with admin user (admin/admin)
- Update CLAUDE.md with migration workflow documentation
- Various frontend fixes (queries, pages, hooks)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/admin/components/dashboard/DashProfile.tsx

@@ -89,6 +89,21 @@ export default function DashProfile({
   const handleSubmit = async (e?: React.FormEvent) => {
     e?.preventDefault();
     const dataToSave = { ...formData };
+
+    if (dataToSave.new_password && !dataToSave.current_password) {
+      alert.error("Pro změnu hesla zadejte aktuální heslo");
+      return;
+    }
+    if (dataToSave.current_password && !dataToSave.new_password) {
+      alert.error("Pro změnu hesla zadejte nové heslo");
+      return;
+    }
+
+    // Strip empty password fields so Zod doesn't reject ""
+    if (!dataToSave.current_password)
+      delete (dataToSave as any).current_password;
+    if (!dataToSave.new_password) delete (dataToSave as any).new_password;
+
     try {
       const response = await apiFetch(`${API_BASE}/profile`, {
         method: "PUT",
@@ -329,9 +344,24 @@ export default function DashProfile({
                       className="admin-form-input"
                     />
                   </div>
+                  <div className="admin-form-group">
+                    <label className="admin-form-label">Aktuální heslo</label>
+                    <input
+                      type="password"
+                      value={formData.current_password}
+                      onChange={(e) =>
+                        setFormData({
+                          ...formData,
+                          current_password: e.target.value,
+                        })
+                      }
+                      className="admin-form-input"
+                      placeholder="Pro změnu hesla, zadejte aktuální heslo"
+                    />
+                  </div>
                   <div className="admin-form-group">
                     <label className="admin-form-label">
-                      Nové heslo (ponechte prázdné pro zachování stávajícího)
+                      Nové heslo
                     </label>
                     <input
                       type="password"
@@ -343,27 +373,9 @@ export default function DashProfile({
                         })
                       }
                       className="admin-form-input"
+                      placeholder="Pro změnu hesla, zadejte nové heslo"
                     />
                   </div>
-                  {formData.new_password && (
-                    <div className="admin-form-group">
-                      <label className="admin-form-label required">
-                        Aktuální heslo
-                      </label>
-                      <input
-                        type="password"
-                        value={formData.current_password}
-                        onChange={(e) =>
-                          setFormData({
-                            ...formData,
-                            current_password: e.target.value,
-                          })
-                        }
-                        className="admin-form-input"
-                        placeholder="Zadejte aktuální heslo pro potvrzení"
-                      />
-                    </div>
-                  )}
                 </div>
               </div>
               <div className="admin-modal-footer">