portfolio-edit: edit-mode toggle scaffold

app/static/js/portfolio_edit.js

@@ -0,0 +1,43 @@
+/* Dashboard-native portfolio editing.
+ *
+ * Owns: the EDIT button toggle, the add-position form behaviour
+ * (ticker validation on blur, qty/cost inputs, date-mode historical
+ * lookup, Add click), and per-row delete via event delegation.
+ *
+ * Reads/writes the portfolio via window.CassandraPortfolio.loadPie /
+ * savePie / mountAndRender — the same surface portfolio.js exposes
+ * for the CSV-import preview.
+ */
+(function () {
+  'use strict';
+
+  const panel    = document.getElementById('portfolio-panel');
+  const editBtn  = document.getElementById('pf-edit-btn');
+  const doneBtn  = document.getElementById('pf-done-btn');
+  const form     = document.getElementById('pf-add-form');
+  if (!panel || !editBtn || !doneBtn || !form) return;
+
+  function enterEditMode() {
+    panel.classList.add('pf-editing');
+    form.hidden = false;
+    editBtn.hidden = true;
+    doneBtn.hidden = false;
+    editBtn.setAttribute('aria-pressed', 'true');
+    document.getElementById('pf-add-ticker').focus();
+  }
+
+  function exitEditMode() {
+    panel.classList.remove('pf-editing');
+    // Form stays visible when the pie is empty (empty-state UX handled
+    // by portfolio.js setting the pf-empty class on the panel).
+    if (!panel.classList.contains('pf-empty')) {
+      form.hidden = true;
+    }
+    editBtn.hidden = false;
+    doneBtn.hidden = true;
+    editBtn.setAttribute('aria-pressed', 'false');
+  }
+
+  editBtn.addEventListener('click', enterEditMode);
+  doneBtn.addEventListener('click', exitEditMode);
+})();