ui: put the decoded FCI in a named bordered block (v2.7.12)

The file manager's decoded FCI rows now sit in a fieldset matching the
phone-simulator containers, with the symbolic file name as its legend
(pysimFsInfoHtml(sel, name)); the metadata line stays above the border.
Without a name the fieldset renders without a legend, and without
fci_hex no block is shown at all.

- tests: fieldset/legend markup, metadata line before the border, no
  legend without a name, escaped legend text, no fieldset without FCI.
- help EN/RU mention the named FCI block.

frontend/tests/html.test.js

@@ -205,7 +205,7 @@ test('file manager shows FCI info and keeps the selection in state, not the DOM'
     const content = html.indexOf('id="pysim-fs-content"');
     assert.ok(detail !== -1 && info > detail && info < content, 'pysim-fs-info must sit above the content');
     assert.ok(html.includes('function pysimFsInfoHtml'));
-    assert.ok(html.includes("pysimFsInfoHtml(sel)"));
+    assert.ok(html.includes('pysimFsInfoHtml(sel, name)'));
     assert.ok(!html.includes('pysim-fs-filename'));
     assert.ok(html.includes('let pysimFsSelected = null;'));
     assert.ok(html.includes('pysimFsSelected = name;'));