Add Input/InputBind/InputButton JS bindings, move default binds to JS

Adds a new script module exposing Input.bind/value/lastValue/isDown/
wasDown/pressed/released, InputBind.* (the inputbind_t action enum),
and InputButton.* (every named button in the compiled platform's
INPUT_BUTTON_DATA table, e.g. InputButton.SELECT on PSP).

Renames the PLATFORM global to Platform.current for consistency with
Time/Console/Input.

Uppercases every INPUT_BUTTON_DATA .name across inputlinux.c/
inputpsp.c/inputdolphin.c to match the InputButton.* JS constants
(inputButtonGetByName was already case-insensitive, so this doesn't
change matching behavior).

Moves the default key/button-to-action bindings out of
src/duskrpg/input/inputbindmap.h (deleted) and into
assets/scripts/input.js, branching on Platform.current instead of the
old per-platform #ifdefs. Wired in via require('./input.js') from
init.js.

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

test/script/test_moduleplatform.c

@@ -0,0 +1,46 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "dusktest.h"
+#include "script/scriptmanager.h"
+#include "script/module/modulebase.h"
+
+static int platform_setup(void **state) {
+  errorret_t ret = scriptManagerInit();
+  if(errorIsNotOk(ret)) { errorCatch(ret); return -1; }
+  return 0;
+}
+
+static int platform_teardown(void **state) {
+  errorret_t ret = scriptManagerDispose();
+  if(errorIsNotOk(ret)) errorCatch(ret);
+  return 0;
+}
+
+static void test_platform_current_matches_target_system(void **state) {
+  jerry_value_t result;
+  errorret_t ret = scriptManagerExec("Platform.current;", &result);
+  assert_true(errorIsOk(ret));
+  assert_true(jerry_value_is_string(result));
+
+  char_t buf[32];
+  moduleBaseToString(result, buf, sizeof(buf));
+  assert_string_equal(buf, DUSK_TARGET_SYSTEM);
+
+  jerry_value_free(result);
+}
+
+int main(void) {
+  assertInit();
+  const struct CMUnitTest tests[] = {
+    cmocka_unit_test_setup_teardown(
+      test_platform_current_matches_target_system,
+      platform_setup, platform_teardown
+    ),
+  };
+  return cmocka_run_group_tests(tests, NULL, NULL);
+}