Bootstrap DD3 Rust port workspace with host-first compatibility tests

fuzz/fuzz_targets/url_encode_component.rs

@@ -0,0 +1,8 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    if let Ok(s) = core::str::from_utf8(data) {
+        let _ = dd3_contracts::url_encode_component(s);
+    }
+});