Revert Filesystem to origin/main

Author: rtfeldman

src/fs/mod.zig

@@ -3,14 +3,4 @@
 //! This module provides a filesystem interface that allows for easy testing
 //! and mocking of file operations throughout the compiler.
 
-const std = @import("std");
-const builtin = @import("builtin");
-
-/// Maximum file size constant - available without importing Filesystem
-pub const max_file_size = std.math.maxInt(u32);
-
-/// Filesystem abstraction that works on all platforms.
-/// On WASM, provides a minimal stub since std.posix is not available on wasm32-freestanding.
-pub const Filesystem = if (builtin.cpu.arch == .wasm32) struct {
-    pub const max_file_size = @This().max_file_size;
-} else @import("Filesystem.zig");
+pub const Filesystem = @import("Filesystem.zig");