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/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"