refactor(control): introduce runtime and SQMA law modules

Separate traffic sampling and shaper access from measurement processing and rate decisions through Runtime, LawContext, and SqmaLaw. Add the async Law interface and its dependency; the worker migration activates these modules in the following commit.

Cargo.toml

@@ -20,6 +20,7 @@ strip = "symbols"
 
 [dependencies]
 anyhow = "1.0"
+async-trait = "0.1.92"
 config = { version = "0.15.27", default-features = false }
 csv = "1.4.0"
 fastrand = "2"