feat: name the pad inside muxterm

gptokeyb2 owns the pad in muxterm on muOS with PortMaster, and muxterm keeps PgUp and PgDn for its scrollback. The launcher now says so with RETROBIOS_PAD=gptokeyb_muxterm, and the hints name the gptokeyb buttons with no paging key.

install.py

@@ -10039,7 +10039,7 @@ def plain_requested(args: argparse.Namespace, env: Mapping[str, str] | None = No
 # (ports/shared/tui.txt exports RB_PAD as this), so the bar names those
 # buttons and no others.
 TUI_PAD_ENV = "RETROBIOS_PAD"
-TUI_PAD_ROUTES = ("gptokeyb", "muxterm", "evmapy", "miyoo")
+TUI_PAD_ROUTES = ("gptokeyb", "gptokeyb_muxterm", "muxterm", "evmapy", "miyoo")
 # Set by Steam for what it starts, and by gamescope: a controller may be
 # all there is, mapped by Steam Input to keys nobody here can name.
 _STEAM_MARKERS = ("SteamGamepadUI", "SteamDeck", "SteamGameId", "GAMESCOPE_WAYLAND_DISPLAY")
@@ -10251,6 +10251,7 @@ def _filter_row(state: TuiState) -> TuiRow:
         return TuiRow("filter", f"Filter: {text}")
     # A pad has no / and no letters: muxterm's own keyboard types.
     how = {"muxterm": "Select shows a keyboard", "gptokeyb": "with a keyboard",
+           "gptokeyb_muxterm": "with a keyboard",
            "evmapy": "with a keyboard", "miyoo": "with a keyboard"}.get(state.pad, "/ to type")
     return TuiRow("filter", f"Filter ({how})", style="dim")
 
@@ -11280,6 +11281,9 @@ _ROUTE_KEYS: dict[str, dict[str, str | None]] = {
     "miyoo": {"A/Enter": "A", "B/Esc": "R2", "X/Space": "A", "Y/o": "L2", "?": None,
               "/": None, "Ctrl-C": None, "Enter": "Start", "Esc": None, "Ctrl-U": None},
 }
+# gptokeyb2 with retrobios.gptk inside muxterm, which no longer reads the pad:
+# the gptokeyb buttons.
+_ROUTE_KEYS["gptokeyb_muxterm"] = _ROUTE_KEYS["gptokeyb"]
 
 
 def _route_hint(state: TuiState, parts: tuple) -> tuple:
@@ -11858,6 +11862,7 @@ _STOP_KEYS = {
     "both": ("B or Ctrl-C", "B, Ctrl-C or Start+Select"),
     "keys": ("Esc or Ctrl-C", "Esc or Ctrl-C"),
     "gptokeyb": ("B", "B or Start+Select"),
+    "gptokeyb_muxterm": ("B", "B or Start+Select"),
     "evmapy": ("B", "B"),
     "muxterm": ("B", "B"),
     "miyoo": ("R2", "R2"),
@@ -12124,6 +12129,9 @@ _HELP_KEYS: dict[str, dict[str, str | None]] = {
               "back": "R2, Esc, Backspace", "stop": "R2, Esc, Ctrl-C", "kill": None,
               "enter": "Start, Enter", "esc": "Esc"},
 }
+# muxterm keeps PgUp and PgDn for its scrollback even when gptokeyb2 owns the
+# pad, and the launcher sends nothing on L1 and R1 there.
+_HELP_KEYS["gptokeyb_muxterm"] = {**_HELP_KEYS["gptokeyb"], "page": None}
 
 
 def _route_extras(state: TuiState) -> list[tuple[str, str]]:
@@ -12140,7 +12148,7 @@ def _help_lines(state: TuiState) -> list[tuple[str, str]]:
     names = _HELP_KEYS.get(state.pad, _HELP_KEYS["both"])
     # gptokeyb's kill: Start pressed first also chooses the row in focus.
     kill = ([(names["kill"], "Quit at once")]
-            if state.pad == "gptokeyb" else [])
+            if state.pad in ("gptokeyb", "gptokeyb_muxterm") else [])
     if screen == "installing":
         return [(names["stop"], "Stop: what is done stays done"),
                 *([(names["kill"], "Stop")] if names["kill"] else []),