Added mass-import and mass-export to admin page.

Styles/Style.css

@@ -2515,3 +2515,190 @@ input, button, textarea, select {
         margin-top: 0;
     }
 }
+
+.AdminTransferPanel {
+    margin-top: 1.5rem;
+    overflow: hidden;
+    box-shadow: 3px 3px 0 var(--Crust);
+}
+
+.AdminTransferPanel[hidden] {
+    display: none;
+}
+
+.AdminTransferPanelHeader {
+    justify-content: space-between;
+}
+
+.AdminTransferPanelHeader h2 {
+    margin-bottom: 0;
+}
+
+.AdminTransferCloseButton {
+    width: auto;
+    min-width: 6rem;
+    padding: 0.35rem 0.65rem;
+}
+
+.AdminTransferPanelBody {
+    padding: 1rem;
+}
+
+.AdminTransferPanelBody > p:first-child {
+    margin-top: 0;
+}
+
+.AdminTransferToolbar,
+.AdminTransferSelectionActions {
+    display: flex;
+    gap: 0.75rem;
+    margin-bottom: 1rem;
+    align-items: center;
+    flex-wrap: wrap;
+}
+
+.AdminTransferToolbar .AdminInlineButton,
+.AdminTransferSelectionActions .AdminInlineButton {
+    width: auto;
+}
+
+.AdminTransferSummary {
+    color: var(--Subtext1);
+}
+
+.AdminTransferSearchControls {
+    grid-template-columns: minmax(0, 1fr) auto;
+}
+
+.AdminTransferCardList {
+    display: flex;
+    flex-direction: column;
+    gap: 1rem;
+}
+
+.AdminTransferCardHeader {
+    flex-wrap: wrap;
+}
+
+.AdminTransferCardMeta {
+    display: flex;
+    margin-left: auto;
+    align-items: center;
+    justify-content: flex-end;
+    gap: 0.65rem;
+    min-width: 0;
+}
+
+.AdminTransferStatus {
+    flex: 0 0 auto;
+    padding: 0.2rem 0.45rem;
+    color: var(--Green);
+    background-color: var(--Surface0);
+    border: 2px solid var(--Green);
+}
+
+.AdminTransferStatusError {
+    color: var(--Red);
+    border-color: var(--Red);
+}
+
+.AdminTransferFileName {
+    min-width: 0;
+    margin: 0;
+    color: var(--Overlay2);
+    overflow-wrap: anywhere;
+}
+
+.AdminTransferErrorCard,
+.AdminTransferCardInvalid {
+    border-color: var(--Red);
+}
+
+.AdminTransferErrorHeader {
+    justify-content: space-between;
+}
+
+.AdminTransferErrorHeader h2 {
+    margin-bottom: 0;
+    color: var(--Red);
+}
+
+.AdminTransferErrorBody {
+    padding: 1rem;
+}
+
+.AdminTransferErrorBody p:last-child {
+    margin-bottom: 0;
+}
+
+.AdminTransferInlineError {
+    margin: 0;
+    padding: 0.75rem 1rem;
+    color: var(--Red);
+    background-color: var(--Mantle);
+    border-top: 3px solid var(--Red);
+}
+
+.AdminTransferSelectableCard {
+    cursor: pointer;
+}
+
+.AdminTransferSelectableCard[data-selected="true"] {
+    border-color: var(--Sky);
+}
+
+.AdminTransferSelectableCard[data-selected="true"] > .PanelHeader {
+    border-bottom-color: var(--Sky);
+}
+
+.AdminTransferSelectToggle {
+    display: flex;
+    margin-left: auto;
+    align-items: center;
+    gap: 0.4rem;
+    color: var(--Subtext1);
+    cursor: pointer;
+}
+
+.AdminTransferSelectToggle input {
+    width: 1.1rem;
+    height: 1.1rem;
+    margin: 0;
+    accent-color: var(--Sky);
+}
+
+.AdminTransferFooter {
+    margin-top: 1rem;
+}
+
+@media (max-width: 700px) {
+    .AdminTransferPanelHeader,
+    .AdminTransferCardHeader,
+    .AdminTransferCardMeta {
+        align-items: flex-start;
+    }
+
+    .AdminTransferPanelHeader {
+        flex-direction: column;
+    }
+
+    .AdminTransferCloseButton {
+        width: 100%;
+    }
+
+    .AdminTransferCardMeta {
+        width: 100%;
+        margin-left: 0;
+        justify-content: flex-start;
+        flex-wrap: wrap;
+    }
+
+    .AdminTransferSearchControls {
+        grid-template-columns: 1fr;
+    }
+
+    .AdminTransferToolbar .AdminInlineButton,
+    .AdminTransferSelectionActions .AdminInlineButton {
+        width: 100%;
+    }
+}