refactor: platform trait, platform-specific code handling into platform module

src/platform/mod.rs

@@ -0,0 +1,58 @@
+//! Platform abstraction layer for cross-platform functionality.
+
+use std::borrow::Cow;
+use std::time::Duration;
+
+use crate::asset::{Asset, AssetError};
+
+pub mod desktop;
+pub mod emscripten;
+
+/// Platform abstraction trait that defines cross-platform functionality.
+pub trait Platform {
+    /// Sleep for the specified duration using platform-appropriate method.
+    fn sleep(&self, duration: Duration);
+
+    /// Get the current time in seconds since some reference point.
+    /// This is available for future use in timing and performance monitoring.
+    #[allow(dead_code)]
+    fn get_time(&self) -> f64;
+
+    /// Initialize platform-specific console functionality.
+    fn init_console(&self) -> Result<(), PlatformError>;
+
+    /// Get canvas size for platforms that need it (e.g., Emscripten).
+    /// This is available for future use in responsive design.
+    #[allow(dead_code)]
+    fn get_canvas_size(&self) -> Option<(u32, u32)>;
+
+    /// Load asset bytes using platform-appropriate method.
+    fn get_asset_bytes(&self, asset: Asset) -> Result<Cow<'static, [u8]>, AssetError>;
+}
+
+/// Platform-specific errors.
+#[derive(Debug, thiserror::Error)]
+#[allow(dead_code)]
+pub enum PlatformError {
+    #[error("Console initialization failed: {0}")]
+    ConsoleInit(String),
+    #[error("Platform-specific error: {0}")]
+    Other(String),
+}
+
+/// Get the current platform implementation.
+#[allow(dead_code)]
+pub fn get_platform() -> &'static dyn Platform {
+    static DESKTOP: desktop::DesktopPlatform = desktop::DesktopPlatform;
+    static EMSCRIPTEN: emscripten::EmscriptenPlatform = emscripten::EmscriptenPlatform;
+
+    #[cfg(not(target_os = "emscripten"))]
+    {
+        &DESKTOP
+    }
+
+    #[cfg(target_os = "emscripten")]
+    {
+        &EMSCRIPTEN
+    }
+}