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>

types/index.d.ts

@@ -13,3 +13,5 @@
 /// <reference path="display/mesh.d.ts" />
 /// <reference path="time/time.d.ts" />
 /// <reference path="console/console.d.ts" />
+/// <reference path="platform/platform.d.ts" />
+/// <reference path="input/input.d.ts" />

types/input/input.d.ts

@@ -0,0 +1,53 @@
+// Copyright (c) 2026 Dominic Masters
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+/**
+ * Input action bindings (see duskrpg's input/inputbind.h). Values are the
+ * native inputbind_t enum ordinals.
+ */
+declare const InputBind: {
+  readonly UP: number;
+  readonly DOWN: number;
+  readonly LEFT: number;
+  readonly RIGHT: number;
+  readonly ACCEPT: number;
+  readonly CANCEL: number;
+  readonly PAUSE: number;
+  readonly RAGEQUIT: number;
+  readonly CONSOLE: number;
+  readonly POINTERX: number;
+  readonly POINTERY: number;
+};
+
+/**
+ * Every named physical button registered in the compiled platform's
+ * INPUT_BUTTON_DATA table (see e.g. src/duskpsp/input/inputpsp.c). The
+ * exact set of keys varies per platform -- e.g. InputButton.SELECT exists
+ * on PSP, InputButton.GAMEPAD_BACK on Linux/SDL2. Each value is just the
+ * button's own name string, suitable for passing straight to Input.bind().
+ */
+declare const InputButton: {
+  readonly [name: string]: string;
+};
+
+/**
+ * Live input state, keyed by InputBind action (not by InputButton).
+ */
+declare const Input: {
+  /** Binds a named physical button (see InputButton) to an action. */
+  bind(button: string, action: number): void;
+  /** Current value of an action (0.0-1.0, or -1.0-1.0 for pointer axes). */
+  value(bind: number): number;
+  /** Value of an action as of the previous update. */
+  lastValue(bind: number): number;
+  /** True if the action is currently held down. */
+  isDown(bind: number): boolean;
+  /** True if the action was held down as of the previous update. */
+  wasDown(bind: number): boolean;
+  /** True if the action was just pressed this update (down now, not before). */
+  pressed(bind: number): boolean;
+  /** True if the action was just released this update (up now, down before). */
+  released(bind: number): boolean;
+};

types/platform/platform.d.ts

@@ -0,0 +1,12 @@
+// Copyright (c) 2026 Dominic Masters
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+/**
+ * The engine's compile-time target system (see DUSK_TARGET_SYSTEM).
+ */
+declare const Platform: {
+  /** e.g. "linux", "psp", "wii", "gamecube", "knulli". */
+  readonly current: string;
+};