chore: import upstream snapshot with attribution

examples/zero-hash/src/input.0

@@ -0,0 +1,5 @@
+pub fn seed(fs: Fs) -> Void raises [NotFound, TooLarge, Io] {
+    var file: owned<File> = check std.fs.createOrRaise(fs, ".zero/zero-hash-input.txt")
+    check std.fs.writeAllOrRaise(&mut file, std.mem.span("zero hash payload\n"))
+    std.fs.close(&mut file)
+}

examples/zero-hash/src/main.0

@@ -0,0 +1,22 @@
+use input
+
+pub fn main(world: World) -> Void raises [NotFound, TooLarge, Io] {
+    let fs: Fs = std.fs.host()
+    check seed(fs)
+    var storage: [64]u8 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
+    var alloc: FixedBufAlloc = std.mem.fixedBufAlloc(storage)
+    let arg_path: Maybe<String> = std.args.get(1)
+    var path: String = ".zero/zero-hash-input.txt"
+    if arg_path.has {
+        path = arg_path.value
+    }
+    let body: Maybe<owned<ByteBuf>> = std.fs.readAll(alloc, fs, path, 64)
+    if body.has {
+        var buf: owned<ByteBuf> = body.value
+        let bytes: MutSpan<u8> = std.mem.bufBytes(&buf)
+        let checksum: u32 = std.codec.crc32Bytes(bytes)
+        if checksum == 1120241454 {
+            check world.out.write("zero-hash ok\n")
+        }
+    }
+}

examples/zero-hash/zero.toml

@@ -0,0 +1,7 @@
+[package]
+name = "zero-hash"
+version = "0.1.0"
+
+[targets.cli]
+kind = "exe"
+main = "src/main.0"