Console help: revert to command listing; hide connect alias.

`help` bare went back to printing the textual list of commands rather
than opening the help screen — the screen is reachable from the
dashboard with `[h]`. This matches how every other CLI handles `help`
and avoids surprising script behaviour.

Added a `hidden` field on `CommandSpec` so registry-level aliases can
be excluded from the listing. `connect` is now hidden (the alias
`plug` is the user-facing name on the dashboard and in `help`).
Both names continue to resolve to the same action; existing scripts
that used `connect` still work.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/tui/tui.hpp

@@ -35,6 +35,7 @@ class Tui {
         std::string description;
         bool scriptable = true;
         bool interactive = false;  ///< opens a full-screen mode when called bare
+        bool hidden = false;       ///< don't list in `help` (used by aliases)
     };
 
     // ---- Shell state ----