Keep the keyboard on the grid after the formula bar; editor uses cell colours

- Enter/Escape in the formula bar (and a jump via the Name Box) hand the
  focus back to the table of the selection, so the arrow keys move the
  active cell again instead of doing nothing.
- The in-cell editor takes the cell's own text/fill colour and bold/
  italic, so a light-on-dark cell no longer turns into dark text on a
  dark fill while editing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/frontend/components/FormulaBar.vue

@@ -66,7 +66,7 @@ function onNameInput() {
  *  in this app. */
 function jumpTo(text: string) {
   if (store.jumpToNameInput(text)) {
-    (document.activeElement as HTMLElement)?.blur();
+    backToGrid();
   } else {
     toast.error(`„${text}" ist kein gültiger Bezug oder Name.`);
     nextTick(() => nameEl.value?.select());
@@ -102,6 +102,15 @@ function onNameKeydown(e: KeyboardEvent) {
   }
 }
 
+/** Leave the bar and hand the keyboard back to the grid of the selected
+ *  table, so the arrow keys move the active cell again (just blurring
+ *  would leave nothing focused). */
+function backToGrid() {
+  (document.activeElement as HTMLElement)?.blur();
+  const tableId = store.doc.selection?.tableId;
+  if (tableId) window.dispatchEvent(new CustomEvent('numolus:focus-grid', { detail: tableId }));
+}
+
 function commit() {
   const sel = store.doc.selection;
   if (sel) store.setCellInput(sel.tableId, sel.anchor.col, sel.anchor.row, draft.value);
@@ -134,7 +143,7 @@ function onFocus() {
 }
 function onEnter() {
   commit();
-  (document.activeElement as HTMLElement)?.blur();
+  backToGrid();
 }
 function onBlur() {
   focused.value = false;
@@ -144,7 +153,7 @@ function onBlur() {
 }
 function onEscape() {
   draft.value = store.activeCellInput.value;
-  (document.activeElement as HTMLElement)?.blur();
+  backToGrid();
 }
 /** Actual typing (not a point-mode click inserting a reference programmatically)
  *  ends the "next click replaces the last reference" window. */