feat(help): open a generated command reference instead of Discussions (#1049)

HELP now opens docs/command-reference.md on GitHub — a 600-command
reference grouped by category with default shortcuts and selection
behavior, generated from the in-repo command registry. A staleness
test fails when the registry and the page drift apart; regenerate
with UPDATE_COMMAND_REFERENCE=1 cargo test command_reference. The
command-line notice is localized in all 21 languages.

locales/it-IT/opencadstudio.ftl

@@ -3562,6 +3562,7 @@ view =
     .objectscale-the-active-annotation-scale-is-una = OBJECTSCALE: la scala di annotazione attiva non è disponibile.
     .opening-ocs-discussions-for-help-and-questions = Apertura delle discussioni OCS per assistenza e domande...
     .opening-ocs-web = Apertura del Web OCS...
+    .opening-the-command-reference = Apertura del riferimento dei comandi...
     .opening-patreon-page = Apertura della pagina Patreon...
     .opening-feedback-page = Apertura della pagina di feedback...
     .opening-release-notes = Note sulla versione di apertura...