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/fault/src/lib.rs

@@ -0,0 +1,21 @@
+mod bindings {
+    wit_bindgen::generate!({
+        path: "wit",
+        world: "fault-component",
+    });
+}
+
+struct Fault;
+
+impl bindings::Guest for Fault {
+    fn init(_config: Vec<u8>) -> Result<(), bindings::ServiceError> {
+        Ok(())
+    }
+
+    fn invoke(input: Vec<u8>) -> Result<Vec<u8>, bindings::ServiceError> {
+        assert_ne!(input, b"fault", "intentional test fault");
+        Ok(input)
+    }
+}
+
+bindings::export!(Fault with_types_in bindings);