test scripts: known-file picker for the file actions

The UPDATE file / READ file step editor's path field gains the selector
the APDU builder's SELECT rows use: the loaded file-manager tree, the
custom files and the standard uicc_files.json list, merged by
rfmFileEntries, grouped by root with a filter.  Picking a file fills
test-f-path; the text field stays authoritative (a name path or an
unlisted file can still be typed) and the current path is preselected
when known.  Only EFs are offered - the action reads/writes a file, so a
DF/ADF is not a target.

v3.38.0: server.py VERSION, pyproject.toml and the PWA header;
sw cache simple-v478 (help/index changed); a CHANGELOG [3.38.0] section,
the help EN/RU, docs/test-scripts.md and the AGENTS notes.

Tests: frontend/tests/testscripts.test.js - the option list/grouping, the
EF-only filter, the filter input, the pick->path fill and the form's
picker render for write and read.  1061 Python + 1071 frontend.

CHANGELOG.md

@@ -9,6 +9,19 @@ every change carries a descriptive commit message.
 
 ## [Unreleased]
 
+## [3.38.0] — 2026-10-24
+
+### Added
+
+- **Known-file picker in the test-script file actions.**  The `UPDATE file` /
+  `READ file` step editor's path field gains the selector the APDU builder's
+  SELECT rows use: the file-manager tree, the custom files and the standard
+  file list (`uicc_files.json`), grouped by root with a filter, filling the
+  path.  Only EFs are offered (the action reads/writes a file; a DF/ADF is not
+  a target); the text field stays authoritative, so a name path or a file the
+  lists do not carry can still be typed, and the picker preselects the current
+  path when it is known.
+
 ## [3.37.0] — 2026-10-23
 
 ### Added