fix: use the card's own SimCardCommands for ADM and AUTHENTICATE (v2.7.20)

/api/verify-adm sent VERIFY with CLA A0 on a UICC (SW 6E00) while
pySim-shell's verify_adm worked: fast init builds the card on its own
SimCardCommands instance, but __main__ kept server.scc at the startup
placeholder left at the SIM defaults; only an equip repointed it.

- __main__ adopts card._scc after init (cat_cla still set on it), so
  server.scc carries the card's cla_byte/sel_ctrl from startup on.
- _verify_adm prefers app.rs.lchan[0].scc / app.card._scc, exactly like
  pySim-shell's verify_adm, independent of server.scc.
- netsim AUTHENTICATE follows the card class: a UICC gets 00 88 00 81 22
  (RAND+AUTN, DB/DC response), a SIM gets A0 88 00 00 10 (RAND only,
  SRES+Kc); the 61xx GET RESPONSE uses the same CLA.
- tests: ADM with a stale placeholder scc; 2G builder/parser; SIM-CLA
  runner case; help EN/RU and AGENTS updated.

frontend/index.html

@@ -1414,7 +1414,7 @@
 // ===== Version =====
 // Single source of truth for the PWA version: shown in the header and used
 // by the server version check in pysimConnect().
-const SIMPLE_VERSION = '2.7.19';
+const SIMPLE_VERSION = '2.7.20';
 document.getElementById('app-version').textContent = 'v' + SIMPLE_VERSION;
 
 // ===== Tab switching =====