v3.28.4: the Custom-mode FCI editor + the shared ADM pattern

The profile rule editor rendered the same "FCI hex (raw SELECT response)"
field for Exact and Custom, although the custom check never reads
`fciHex` (it compares the data objects against the card's live FCI) - so
the field looked like an expectation it was not.

- The raw-FCI field and its decoded preview are exact-mode-only now; the
  Custom mode shows just its data-object editor.
- Switching a rule to Custom seeds the data objects from its captured FCI
  when the list is empty (the same all-'value' seeding a captured profile
  gets); the "load from the captured FCI" link refills an emptied list,
  and a rule without a captured FCI still starts empty for manual rows.

From the v3.28.3 review: the ADM's byte-pair rule now lives in one
place, presets.ADM_PATTERN, used by /api/verify-adm and the outfile
import - two literals could drift and an imported ADM could silently
become unverifiable.  The RU help's ADM wording is "4-16 hex-цифр
(чётное число)".

Docs: help EN/RU, the repo AGENTS.  Tests: the mode switch (seed / keep /
no FCI / switch-away), the field-gating source pin, the pattern's shape
and the both-users pin.  917 frontend + 927 Python; sw cache simple-v442.

tests/test_presets.py

@@ -9,6 +9,7 @@ without silently destroying it.
 
 import json
 import pathlib
+import re
 import tempfile
 import unittest
 
@@ -610,5 +611,24 @@ class StoreInfoTests(unittest.TestCase):
         self.assertEqual(presets.default_path().parent.name, '.pysim-simple-server')
 
 
+class AdmPatternTests(unittest.TestCase):
+    """The ADM's shared shape (v3.28.3 review): one constant, used by both the
+    outfile import and /api/verify-adm - two literals would drift and an
+    imported ADM could silently become unverifiable."""
+
+    def test_the_pattern_is_byte_pairs_of_4_to_16_digits(self):
+        for ok in ('1234', '3632333239463337', 'CFA3DD9C6B7F0F8C', '1a2b'):
+            self.assertIsNotNone(re.fullmatch(presets.ADM_PATTERN, ok.upper()), ok)
+        for bad in ('123', '12345', 'AB' * 9, 'ZZZZ', ''):
+            self.assertIsNone(re.fullmatch(presets.ADM_PATTERN, bad), bad)
+
+    def test_both_users_reference_the_constant(self):
+        root = pathlib.Path(__file__).resolve().parents[1]
+        for rel in ('pysim_simple_server/outfile.py', 'pysim_simple_server/server.py'):
+            src = (root / rel).read_text(encoding='utf-8')
+            self.assertIn('presets.ADM_PATTERN', src)
+            self.assertNotIn(r"'(?:[0-9A-F]{2}){2,8}'", src)
+
+
 if __name__ == '__main__':
     unittest.main()