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/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "clock-probe-component"
+version = "0.1.0"
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+
+[package.metadata.wasmeld]
+id = "clock-probe"
+world = "component:clock-probe/clock-probe-component@0.1.0"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+wit-bindgen.workspace = true

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);

components/clock-probe/wasmeld.toml

@@ -0,0 +1,11 @@
+schema_version = 1
+
+[dependencies]
+"wasmeld:clock" = "0.1.0"
+"wasmeld:service" = "0.1.0"
+
+[replace."wasmeld:clock"]
+path = "../../wit/clock"
+
+[replace."wasmeld:service"]
+path = "../../wit/service"

components/clock-probe/wit.lock

@@ -0,0 +1,15 @@
+schema_version = 1
+
+[[package]]
+name = "wasmeld:clock"
+version = "0.1.0"
+source = "path+../../wit/clock"
+sha256 = "93079c69d1b9cb3afc28da6fe4a7e37f724d0a09e780c847f8524d3920a90960"
+replaced = true
+
+[[package]]
+name = "wasmeld:service"
+version = "0.1.0"
+source = "path+../../wit/service"
+sha256 = "d5497307bbcd1e159f7707f385b488a6f2e26362d5256d5bc1080ac603a51305"
+replaced = true

components/clock-probe/wit/world.wit

@@ -0,0 +1,6 @@
+package component:clock-probe@0.1.0;
+
+world clock-probe-component {
+  include wasmeld:service/service-component@0.1.0;
+  import wasmeld:clock/monotonic-clock@0.1.0;
+}