ui: fix net-sim i18n — decode-entity key match + label coverage (v2.7.6)

The network-simulation description never switched to Russian: its
data-l10n attribute carries " (decoded to " by the browser), while the
LANG_RU key is raw text inside <script> and keeps the literal &quot;, so
translatePage()'s lookup missed and t() returned the English key.

- LANG_RU: the description key now carries real quotes, matching the
  decoded attribute value (RU value unchanged)
- add the missing RU entries for the net-sim labels AUTHENTICATE, MCC,
  MNC, LAC, Cell ID, TAC, RAC (acronyms map to themselves; Cell ID ->
  «Идентификатор соты»)
- html.test.js: strict cross-check that every data-l10n attribute
  (entity-decoded, as the browser does) is a LANG_RU key
- sw.js cache simple-v209; version trio 2.7.6

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pysim-simple-server"
-version = "2.7.5"
+version = "2.7.6"
 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.