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/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