fix(input): keys are physical positions on every layout; Input.key_label names them

The Windows runtime keyed the held set by the character MapVirtualKeyA gave a
virtual key, so a game's WASD belonged to whatever the active layout put there,
and with an input method on every letter arrived as VK_PROCESSKEY. The typing
block is now read from the scancode (the arrows, numpad and F-keys still by
virtual key); macOS reads keyCode the same way. Input.key_label(key) names a key
in the player's own layout (Windows) or as its US character elsewhere.

Verified on Windows with SendInput into a live window: VK_Z carrying W's scancode
holds 'w', VK_PROCESSKEY carrying A's holds 'a', Caps Lock changes nothing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

selfhost/backend/emit_call.ludic

@@ -449,6 +449,7 @@ function emit_ns_call(ns: pointer, meth: pointer, e: Node) -> Val {
     if (meth == "key_down")     { bare = "input_key_down";     push(labels, "key") }
     if (meth == "key_pressed")  { bare = "input_key_pressed";  push(labels, "key") }
     if (meth == "key_released") { bare = "input_key_released"; push(labels, "key") }
+    if (meth == "key_label")    { bare = "input_key_label";    push(labels, "key") }
     if (meth == "press")        { bare = "input_press";        push(labels, "key") }
     if (meth == "release")      { bare = "input_release";      push(labels, "key") }
     if (meth == "axis")         { bare = "input_axis";         push(labels, "neg"); push(labels, "pos") }

selfhost/backend/emit_head.ludic

@@ -108,6 +108,7 @@ function emit_header() -> void {
   emith("declare i32 @win_running()\n")
   emith("declare void @win_close()\n")
   emith("declare void @win_held(ptr)\n")
+  emith("declare i32 @win_key_char(i32)\n")
   emith("declare void @win_mouse(ptr)\n")
   emith("declare void @win_pad(ptr)\n")
   emith("declare void @win_touch(ptr)\n")

selfhost/backend/emit_intrin2.ludic

@@ -21,6 +21,7 @@ function is_intrinsic2(name: pointer) -> bool {
   if (name == "win_open") or (name == "win_poll") or (name == "win_present") { return true }
   if (name == "win_running") or (name == "win_close") { return true }
   if (name == "win_held") or (name == "win_mouse") { return true }   # #50 device layer
+  if (name == "win_key_char") { return true }                        # Input.key_label
   if (name == "win_pad") or (name == "win_touch") { return true }    # #51 gamepad / touch
   if (name == "win_cursor_mode") { return true }                     # #89 cursor capture
   if (name == "snd_load") or (name == "snd_play") or (name == "snd_stop") { return true }   # #22 audio
@@ -71,6 +72,9 @@ function emit_intrinsic2(name: pointer, e: Node) -> Val {
   # button-mask, wheel-delta].
   if (name == "win_held")  { let a = arg_code(e, 0);  emit("  call void @win_held(ptr ");  emit(a);  emit(")\n");  return val("0", "void") }
   if (name == "win_mouse") { let a = arg_code(e, 0);  emit("  call void @win_mouse(ptr ");  emit(a);  emit(")\n");  return val("0", "void") }
+  # what the active keyboard layout types on a held-set key position (windowed only,
+  # DCE'd headless): a code point, 0 for none.
+  if (name == "win_key_char") { let a = arg_code(e, 0);  return val(emit_bind(`call i32 @win_key_char(i32 {a})`), "int") }
   # #51 — win_pad: 6 words/pad [connected, mask, lx, ly, rx, ry]; win_touch: 3
   # words/point [active, x, y]. Both windowed-only, DCE'd headless.
   if (name == "win_pad")   { let a = arg_code(e, 0);  emit("  call void @win_pad(ptr ");  emit(a);  emit(")\n");  return val("0", "void") }

selfhost/frontend/parse.ludic

@@ -241,7 +241,7 @@ function p_postfix() -> Node {
       if e.a.kind == E_ID and e.a.s == "Input" and (e.s == "bind" or e.s == "rebind" or e.s == "poll" or e.s == "down" or e.s == "pressed" or e.s == "record" or e.s == "replay" or e.s == "action" or e.s == "bind_pad" or e.s == "active" or e.s == "just_pressed" or e.s == "just_released") { g_uses_input = true }
       # #50 device layer — any of the multi-key / analog / mouse / gamepad / touch
       # methods also splices input.ludic (Input.key stays bare, no runtime).
-      if e.a.kind == E_ID and e.a.s == "Input" and (e.s == "key_down" or e.s == "key_pressed" or e.s == "key_released" or e.s == "press" or e.s == "release" or e.s == "axis" or e.s == "axis_i" or e.s == "vector" or e.s == "strength" or e.s == "mouse_x" or e.s == "mouse_y" or e.s == "mouse_dx" or e.s == "mouse_dy" or e.s == "mouse_down" or e.s == "wheel" or e.s == "set_mouse" or e.s == "pad_connected" or e.s == "pad_button" or e.s == "pad_axis" or e.s == "move_i" or e.s == "set_pad" or e.s == "touch_count" or e.s == "touch_x" or e.s == "touch_y" or e.s == "set_touch" or e.s == "cursor_mode") { g_uses_input = true }
+      if e.a.kind == E_ID and e.a.s == "Input" and (e.s == "key_down" or e.s == "key_pressed" or e.s == "key_released" or e.s == "key_label" or e.s == "press" or e.s == "release" or e.s == "axis" or e.s == "axis_i" or e.s == "vector" or e.s == "strength" or e.s == "mouse_x" or e.s == "mouse_y" or e.s == "mouse_dx" or e.s == "mouse_dy" or e.s == "mouse_down" or e.s == "wheel" or e.s == "set_mouse" or e.s == "pad_connected" or e.s == "pad_button" or e.s == "pad_axis" or e.s == "move_i" or e.s == "set_pad" or e.s == "touch_count" or e.s == "touch_x" or e.s == "touch_y" or e.s == "set_touch" or e.s == "cursor_mode") { g_uses_input = true }
       # Anim.play/clip/on_frame/fired + Motion.to (#48): the ergonomic writes over
       # the SpriteAnim/Motion components live in systems.ludic and use the world
       # table, so splice it and force the reflection ABI even if the game leaves