feat: every key on the keyboard is bindable - the F-row, the six-pack, Caps Lock and the numpad

The platform gave these keys no code at all, so a game's rebinding screen could not take
one and nothing said why. Windows asked the active layout what they type and got nothing
(w_vk_char answers 0 for a key with no character); macOS let them fall through to
charactersIgnoringModifiers, which reports NSF1FunctionKey and its neighbours at 0xF704
and up - outside the 256-bit held set either way.

w_keyval and ev_keyval now name them, with the same codes on both: 132-143 F1-F12,
144-149 Home / End / PageUp / PageDown / Insert / Delete, 150 Caps Lock, 152-161 the
numpad digits, 162-166 its * + - . and /. The numpad's Enter is Enter.

Key.F1, Key.Home, Key.Numpad0 and the rest fold at compile time, and Input.key_label
names them without asking the layout - a key that types nothing is called the same thing
on every layout.

examples/library/input_typeless_keys.ludic covers the codes, the names, the held set and
the press edge; 150 passed in ludic-dev test, 33 in selfhost-test.

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

docs/language/input/input-key_down.md

@@ -11,7 +11,7 @@ ns: Input
 member: key_down
 ---
 
-Returns whether a physical <code>key</code> is held this frame — from the platform when windowed, from the polled key when headless, and from <a href="input-press.html"><code>Input.press</code></a> injection on any target. Unlike the single-key <a href="input-down.html"><code>Input.down</code></a>, several keys can be held at once (move left <em>and</em> jump).
+Returns whether a physical <code>key</code> is held this frame — from the platform when windowed, from the polled key when headless, and from <a href="input-press.html"><code>Input.press</code></a> injection on any target. Unlike the single-key <a href="input-down.html"><code>Input.down</code></a>, several keys can be held at once (move left <em>and</em> jump). Every key on the keyboard has a code: letters, digits and punctuation are their US-layout character, Space, Enter, Esc, Tab, Backspace, Shift, Ctrl and Alt their usual ones, the arrows 128-131, and the keys that type nothing 132-166 - F1-F12 at 132, Home, End, PageUp, PageDown, Insert and Delete at 144, Caps Lock at 150, the numpad digits at 152 and its <code>*</code>, <code>+</code>, <code>-</code>, <code>.</code> and <code>/</code> at 162. <code>Key.F1</code>, <code>Key.Home</code> and <code>Key.Numpad0</code> name them.
 
 ```ludic
 program Demo {

docs/language/input/input-key_label.md

@@ -11,7 +11,7 @@ ns: Input
 member: key_label
 ---
 
-Returns the name to show for <code>key</code>. The letter, digit and punctuation codes that <a href="input-key_down.html"><code>Input.key_down</code></a> reads are <em>physical</em> keys, named for what they type on a US layout: <code>'w'</code> is the key above <code>'s'</code> on every keyboard, whatever layout, language, input method or Caps Lock state the player has. So WASD is always under the left hand, and the label is what that key types in the player's layout - <code>"W"</code> on QWERTY, <code>"Z"</code> on AZERTY. Space, Enter, Esc, Tab, Backspace, Shift, Ctrl, Alt and the arrows get words, and a code with no name returns <code>""</code>.
+Returns the name to show for <code>key</code>. The letter, digit and punctuation codes that <a href="input-key_down.html"><code>Input.key_down</code></a> reads are <em>physical</em> keys, named for what they type on a US layout: <code>'w'</code> is the key above <code>'s'</code> on every keyboard, whatever layout, language, input method or Caps Lock state the player has. So WASD is always under the left hand, and the label is what that key types in the player's layout - <code>"W"</code> on QWERTY, <code>"Z"</code> on AZERTY. Space, Enter, Esc, Tab, Backspace, Shift, Ctrl, Alt and the arrows get words, and a code with no name returns <code>""</code>. The keys that type no character - F1-F12, Home, End, PageUp, PageDown, Insert, Delete, Caps Lock and the numpad, codes 132-166 - are named <code>"F1"</code>, <code>"Home"</code>, <code>"CapsLock"</code>, <code>"Num 0"</code>, <code>"Num /"</code> and so on, and the layout is <em>not</em> asked: a key that types nothing is called the same thing on every layout.
 
 On Windows the label is read from the active layout. Headless, on macOS and in the browser it is the US character, upper case.