Files view: the jumped-to record stays selected (v2.6.2)

- focusMessage()/scrollToType() highlighted the target and removed the class
  after 1500 ms, so a Files-row (or map/category) jump looked selected for a
  moment and then lost it; on top of that any re-render (the 500 ms live
  poll, a filter/search change) rebuilt the list and dropped the highlight —
  even for a clicked entry
- the selection is now persistent app state (STATE.selectedIdx): the render
  marks the entry (gap rows included), focusMessage records the index before
  rendering, showDetail records it for plain clicks, scrollToType persists it
  too (clearing the previous highlight), and a new session/capture resets it
  so a stale index cannot mark an unrelated APDU
- tests: a stub-driven focusMessage case (state + detail updated, no render
  and no timer), the filter-clearing case, and source pins for
  renderMessages, focusMessage, scrollToType, showDetail, loadSession and
  startCapture; 527 Python + 58 Node tests
- README/README_RUS: the jump leaves the record selected; PWA_VERSION/
  pyproject/version.py 2.6.2, SW cache simtrace-analyser-v76

README.md

@@ -203,9 +203,10 @@ The Trace tab's side panel has a view selector (*Map* / *Stats* / **Files**;
 a drop-down, since three tab captions no longer fit).  The Files view is a
 trace-wide timeline of file operations — every **Read**, **Update** and
 **Changed on card** row shows the same file name as the Map view, and clicking
-a row jumps straight to the APDU in the trace (the APDU list keeps the
-reader's position: new messages pin the view to the bottom only while the
-reader is already there, so a jump is never pulled away by the live poll).  Rows that carry a recorded change (a
+a row jumps straight to the APDU in the trace and leaves it highlighted
+until another one is focused (the APDU list keeps the reader's position:
+new messages pin the view to the bottom only while the reader is already
+there, so a jump is never pulled away or un-highlighted by the live poll).  Rows that carry a recorded change (a
 card-side change, or an update that wrote or first observed bytes) also offer
 **Details**: a modal showing the full file path (`MF/EF_ICCID (2FE2)`,
 `ADF/EF_IMSI (6F07)`, `DF_GSM_ACCESS/EF_KcGPRS (4F52)`, `AID …/4F09` — the DF