feat: decode the Items Next Action Indicator in proactive commands (v3.5.3)

SET UP MENU / SELECT ITEM items carry an optional Items Next Action Indicator
(TS 102 223 8.24, tag '18'): one byte per item, in list order, coded with the
Table 9.4 values marked "Used for Next Action Indicator".  The decoder ignored
it, so neither the proactive log nor the STK menu showed what the card would
do when an item is selected.

- server: NAI_TYPES whitelist (the ToC-only values - e.g. '26', '27', '47' -
  are reserved there and are ignored, as are '00' and unlisted values),
  _nai_name(), _attach_nai() (a short NAI list leaves the tail without an
  indicator, extra bytes are ignored); _parse_select_item() and
  _parse_setup_menu_items() plus the TERMINAL PROFILE SET UP MENU walk attach
  nai/nai_name to the items; _decode_cmd() renders '1. Menu -> SET UP MENU'.
- PWA: stkMenuNaiSuffix() adds a small gray '<name>' suffix to STK menu items
  that carry an NAI; the proactive log picks the decode up via cmd_decoded.
- tests: SET UP MENU / SELECT ITEM vectors with NAIs, a reserved value that is
  ignored, a short NAI list, and the stkMenuNaiSuffix unit test.
- docs: UICC_SPECS 6.5 gained the '18' Items next action indicator row
  (8.24/9.4); help EN/RU mention the menu suffix; AGENTS files updated.

548 frontend / 413 Python green; version 3.5.3; sw cache simple-v255.

frontend/tests/stk_menu.test.js

@@ -22,6 +22,7 @@ function extractFunc(src, name, asyncFn) {
 }
 
 let code = extractFunc(html, 'stkMenuRespond', true) + '\n';
+code += extractFunc(html, 'stkMenuNaiSuffix') + '\n';
 code += 'globalThis.esc = s => s;\n';
 eval(code);
 
@@ -38,6 +39,14 @@ function setup(response) {
 	return calls;
 }
 
+test('the STK menu item suffix shows the item next action (8.24)', () => {
+	assert.strictEqual(stkMenuNaiSuffix({ id: 1, text: 'Menu', nai: 0x25, nai_name: 'SET UP MENU' }),
+		'\u25b8 SET UP MENU');
+	// no NAI (or a reserved one, which the server drops) -> no suffix
+	assert.strictEqual(stkMenuNaiSuffix({ id: 2, text: 'Info' }), '');
+	assert.strictEqual(stkMenuNaiSuffix(null), '');
+});
+
 test('back with a fetched SELECT ITEM continues the card dialogue', async () => {
 	const data = { type: 'select_item', items: [{ id: 1, text: 'Info' }] };
 	const calls = setup(data);