Blank root panel, asset form as a modal, and a dedicated Statuses page

- Main panel is now blank at the top level ("Select a folder or asset
  from the tree") instead of showing a dashboard - browsing happens in
  the tree, the panel only shows something once you click into it.
  Removed the now-dead DashboardStats/Stats() machinery it depended on.
- Add/Edit Asset no longer takes over the main panel; it opens in
  #assetModal instead; asset_form.html was trimmed down to just the form
  (no more breadcrumb/panel wrapper) since the modal chrome provides the
  title and footer buttons now. The dynamic item-type-fields and submit
  listeners moved from #main-panel's delegation to the modal element's.
- Statuses split out of the General settings page into its own
  /settings/statuses page and sub-nav entry, alongside General, Item
  Types, and Users.

web/static/js/app.js

@@ -14,7 +14,6 @@
   var mainPanel = document.getElementById('main-panel');
   var isAdmin = document.body.classList.contains('role-admin');
   var draggedNode = null;
-  var formReturnContext = { type: 'root', id: '' };
 
   // ---------------------------------------------------------------------
   // Generic helpers
@@ -514,33 +513,32 @@
   }
 
   // ---------------------------------------------------------------------
-  // Asset form (create / edit)
+  // Asset form (create / edit) - shown in a modal
   // ---------------------------------------------------------------------
 
+  var assetModalEl = document.getElementById('assetModal');
+  var assetModal = (assetModalEl && window.bootstrap) ? new bootstrap.Modal(assetModalEl) : null;
+
+  function showAssetModal(html) {
+    if (!assetModal) return;
+    document.getElementById('assetModalBody').innerHTML = html;
+    var form = document.getElementById('assetForm');
+    document.getElementById('assetModalTitle').textContent = form.dataset.title;
+    document.getElementById('assetModalSubmit').textContent = form.dataset.mode === 'edit' ? 'Save Changes' : 'Create Asset';
+    assetModal.show();
+  }
+
   async function loadAssetForm(opts) {
-    formReturnContext = { type: mainPanel.dataset.contextType || 'root', id: mainPanel.dataset.contextId || '' };
     var params = new URLSearchParams();
     if (opts && opts.folderId) params.set('folder_id', opts.folderId);
     var qs = params.toString();
     var html = await fetchText('/app/panel/assets/new' + (qs ? '?' + qs : ''));
-    mainPanel.innerHTML = html;
-    mainPanel.dataset.contextType = 'asset-form';
-    mainPanel.dataset.contextId = '';
+    showAssetModal(html);
   }
 
   async function loadAssetEditForm(id) {
     var html = await fetchText('/app/panel/assets/' + id + '/edit');
-    mainPanel.innerHTML = html;
-    mainPanel.dataset.contextType = 'asset-form';
-    mainPanel.dataset.contextId = id;
-  }
-
-  function cancelAssetForm(btn) {
-    if (btn.dataset.id) {
-      navigateAndSelect('asset', btn.dataset.id);
-    } else {
-      navigateAndSelect(formReturnContext.type, formReturnContext.id);
-    }
+    showAssetModal(html);
   }
 
   async function submitAssetForm(form) {
@@ -569,6 +567,7 @@
     var method = mode === 'edit' ? 'PATCH' : 'POST';
     try {
       var res = await apiFetch(url, { method: method, json: payload });
+      if (assetModal) assetModal.hide();
       await refreshWholeTree();
       await navigateAndSelect('asset', res.id);
     } catch (err) {
@@ -779,18 +778,9 @@
 
       var pageLink = e.target.closest('.panel-page-link');
       if (pageLink) { e.preventDefault(); loadFolderPanelWithFilters(pageLink.dataset.folderId, { page: pageLink.dataset.page }); return; }
-
-      var cancelFormBtn = e.target.closest('[data-action="cancel-asset-form"]');
-      if (cancelFormBtn) { cancelAssetForm(cancelFormBtn); return; }
     });
 
-    mainPanel.addEventListener('change', async function (e) {
-      if (e.target.id === 'assetFormItemType') {
-        var html = await fetchText('/app/forms/asset-fields?item_type_id=' + e.target.value);
-        var container = document.getElementById('asset-fields-container');
-        if (container) container.innerHTML = html;
-        return;
-      }
+    mainPanel.addEventListener('change', function (e) {
       var filterForm = e.target.closest('.panel-filter-form');
       if (filterForm) {
         loadFolderPanelWithFilters(filterForm.dataset.folderId, { page: 1 });
@@ -810,11 +800,6 @@
       if (e.target.matches && e.target.matches('.panel-filter-form')) {
         e.preventDefault();
         loadFolderPanelWithFilters(e.target.dataset.folderId, { page: 1 });
-        return;
-      }
-      if (e.target.id === 'assetForm') {
-        e.preventDefault();
-        submitAssetForm(e.target);
       }
     });
 
@@ -822,6 +807,25 @@
     // onto the tree only; the tree pane is the primary drag surface.
   }
 
+  // The asset create/edit form lives inside #assetModal (injected fresh
+  // each time it's opened), so its dynamic bits are delegated from the
+  // modal element itself rather than from #main-panel.
+  if (assetModalEl) {
+    assetModalEl.addEventListener('change', async function (e) {
+      if (e.target.id === 'assetFormItemType') {
+        var html = await fetchText('/app/forms/asset-fields?item_type_id=' + e.target.value);
+        var container = document.getElementById('asset-fields-container');
+        if (container) container.innerHTML = html;
+      }
+    });
+    assetModalEl.addEventListener('submit', function (e) {
+      if (e.target.id === 'assetForm') {
+        e.preventDefault();
+        submitAssetForm(e.target);
+      }
+    });
+  }
+
   // ---------------------------------------------------------------------
   // Item type custom field admin form (item-types/{id}/edit page)
   // ---------------------------------------------------------------------