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.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pysim-simple-server"
-version = "3.28.3"
+version = "3.28.4"
 description = "HTTP REST server wrapping pysim for the SIMple PWA"
 requires-python = ">=3.8"
 # pysim is a git-only dependency installed explicitly by setup.bat/setup.sh.