cli (debug/theme): display currently used background

sat_frontends/jp/base.py

@@ -189,6 +189,7 @@ class LiberviaCli:
                 'your settings in libervia.conf').format(
                     background=repr(background)
                 ))
+        self.background = background
         if background == 'light':
             C.A_HEADER = A.FG_MAGENTA
             C.A_SUBHEADER = A.BOLD + A.FG_RED

sat_frontends/jp/cmd_debug.py

@@ -199,6 +199,7 @@ class Theme(base.CommandBase):
         pass
 
     async def start(self):
+        print(f"background currently used: {A.BOLD}{self.host.background}{A.RESET}\n")
         for attr in dir(C):
             if not attr.startswith("A_"):
                 continue