v3.28.2: the outfile ADM encoding fix

The ADM column carries the key's hex value (the length varies, 4-16 hex
digits) - the form the preset store and /api/verify-adm use (pySim pads
it with 'f' to the 8 CHV bytes).  The parser treated it as an ASCII
string hex-encoded and either mangled it (3632333239463337 -> 62329F37,
a wrong ADM that would fail VERIFY and consume an attempt) or dropped it
(CFA3DD9C6B7F0F8C - the live report with AM0027_alfa_dsa.out).

- The ADM is stored as-is: non-hex stripped, uppercased, [0-9A-F]{4,16};
  a non-hex or too-short value is dropped with "ADM is not 4-16 hex
  digits".
- _ascii_from_hex() is gone (its only user was the ADM column).
- Docs: help EN/RU, api.md and the repo AGENTS now say "the key's hex
  value, 4-16 hex digits (the length varies)".

Note: presets imported from a BAP-style file before this fix hold the
mangled ADM - re-import or correct them.

Tests: the BAP fixture (the hex as-is), the AM0027 shape, a
short/lowercase value and the drop cases.  Both real samples verified
(BAP 3632333239463337, AM0027 CFA3DD9C6B7F0F8C; the ALFA sample has no
ADM column and is unchanged).  915 frontend + 925 Python; sw cache
simple-v440.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simple-v439';
+const CACHE = 'simple-v440';
 const URLS = [
   'index.html',
   'help.html',