ui: drop the clipboard/paste JSON buttons from Cards and custom files (v2.5.1)

- Cards and Custom files now expose only Export to file (JSON download) and
  Import from file; the Export-as-JSON / Paste & import / Import-JSON-from-
  clipboard buttons and their paste textareas are gone
- import feedback moves to a transient status line (new ioStatus helper);
  cardsImport/pysimCustomImport no longer read the clipboard
- Network simulation parameters: note under the operator form listing the
  scenarios that use the MCC/MNC (EPS/2G attach and SMS received write real
  LAI/RAI/TAI; cold boot, service lost, limited service and roaming denied
  write dummy files keeping the PLMN; churn/CB/AUTHENTICATE do not use it)
- i18n: removed-button entries dropped, note added EN/RU; help EN/RU updated
- guard tests for the button set and the note; SW cache simple-v196

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pysim-simple-server"
-version = "2.5.0"
+version = "2.5.1"
 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.