feat(runtime): add resident Wasmtime actor runtime

- define versioned service and clock WIT contracts
- enforce import allowlists, fuel, epoch, memory, I/O, and mailbox limits
- keep one Store and Component Instance resident per serial Actor
- add echo, counter, fault, spin, and capability probe components
- cover lifecycle, concurrency, sandbox, and fault recovery behavior

components/clock-probe/src/lib.rs

@@ -0,0 +1,24 @@
+mod bindings {
+    wit_bindgen::generate!({
+        path: "wit",
+        world: "clock-probe-component",
+        generate_all,
+    });
+}
+
+struct ClockProbe;
+
+impl bindings::Guest for ClockProbe {
+    fn init(_config: Vec<u8>) -> Result<(), bindings::ServiceError> {
+        Ok(())
+    }
+
+    fn invoke(input: Vec<u8>) -> Result<Vec<u8>, bindings::ServiceError> {
+        let now = bindings::wasmeld::clock::monotonic_clock::now();
+        let mut output = now.to_le_bytes().to_vec();
+        output.extend_from_slice(&input);
+        Ok(output)
+    }
+}
+
+bindings::export!(ClockProbe with_types_in bindings);