ui: show FID, layout and decoded FCI in the file manager detail pane

- selecting an EF now renders an info block between the File: title and
  the contents: FID, file type, size, record length/count (nulls skipped)
  followed by the decoded FCI via the existing profilerFciPreviewItems()
  decoder (no raw hex), matching the snapshot detail view
- pysimFsInfoHtml() is pure and reused by pysimFsClickFile(); the [LF]
  shorthand stays in the title; custom files get the same metadata from
  the temporary select probe
- tests: pysimFsInfoHtml in profiler.test.js (full response, missing
  fci_hex, skipped nulls) and a structural check for #pysim-fs-info;
  help EN/RU and READMEs updated; SW cache v119 -> v120.

frontend/tests/html.test.js

@@ -68,3 +68,12 @@ test('file manager has a probe-all-files button and status line', () => {
     assert.ok(html.includes('onclick="pysimFsProbeAll()"'));
     assert.ok(html.includes('id="pysim-fs-probe-status"'));
 });
+
+test('file manager shows decoded FCI info under the file name', () => {
+    const name = html.indexOf('id="pysim-fs-filename"');
+    const info = html.indexOf('id="pysim-fs-info"');
+    const content = html.indexOf('id="pysim-fs-content"');
+    assert.ok(name !== -1 && info > name && info < content, 'pysim-fs-info must sit between filename and content');
+    assert.ok(html.includes('function pysimFsInfoHtml'));
+    assert.ok(html.includes("pysimFsInfoHtml(sel)"));
+});