feat(input): native gamepad + touch + mouse-position hardware bindings (#51)

Wire the macOS platform side of the #50 device layer, feeding the same state
buffers the read APIs consume — no API changes, purely OS glue.

- mouse: cocoa.ll reads the live cursor via mouseLocationOutsideOfEventStream,
  converted to framebuffer pixels and y-flipped, so windowed games get
  Input.mouse_x/y without injection (W_mx/W_my were never written before).
- gamepad: win_pad polls GCController.controllers each frame, packing extended-
  gamepad buttons (SDL_GameControllerButton order) and thumbsticks (16.16 fixed,
  Y negated for SDL convention) into in_pad_*. Windowed builds now load
  GameController via -needed_framework (its classes are reached by name, so a
  plain -framework link dead-strips it); DCE'd in headless builds.
- touch: the view's NSTouch phase handlers snapshot the touching set into
  in_touch_* (normalizedPosition -> framebuffer pixels).

Web platform.js gains zero-fill stubs for win_held/mouse/pad/touch so a windowed
wasm build resolves the device-layer imports. New test asserts the windowed link
loads GameController. Reseeded; full + selfhost suites green (79 + 29).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

runtime/native/input.ludic

@@ -239,6 +239,27 @@ function input_device_commit(k: int, replaying: int) -> void {
       let mbuf = words(4)                              # [x, y, button-mask, wheel]
       win_mouse(mbuf)
       in_mx = mbuf[0];  in_my = mbuf[1];  in_mbtn = mbuf[2];  in_wheel = mbuf[3]
+      # #51 — feed the platform gamepad + touch state into the same buffers the
+      # read APIs use. Each is windowed-only glue (win_pad / win_touch are DCE'd
+      # in a headless build); on hardware they overwrite the injected state.
+      let pbuf = words(IN_PADS * 6)                     # [conn, mask, lx, ly, rx, ry]/pad
+      win_pad(pbuf)
+      var pi = 0
+      while pi < IN_PADS {
+        let pb = pi * 6
+        input_set_pad(pi, pbuf[pb] != 0, pbuf[pb + 1],
+                      as_fixed(pbuf[pb + 2]), as_fixed(pbuf[pb + 3]),
+                      as_fixed(pbuf[pb + 4]), as_fixed(pbuf[pb + 5]))
+        pi = pi + 1
+      }
+      let tbuf = words(IN_TOUCH * 3)                    # [active, x, y]/point
+      win_touch(tbuf)
+      var ti = 0
+      while ti < IN_TOUCH {
+        let tb = ti * 3
+        input_set_touch(ti, tbuf[tb + 1], tbuf[tb + 2], tbuf[tb] != 0)
+        ti = ti + 1
+      }
     } else {
       in_set_clear(in_dev)
       if k > 0 { in_bit_set(in_dev, k, true) }