feat(log): add bounded diagnostic transport

libs/kaptan-log/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "kaptan-log"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+rust-version.workspace = true
+version.workspace = true
+
+[lints]
+workspace = true
+
+[features]
+default = []
+# Optional allocation-free standard-log ingress. It uses one bounded atomic
+# attempt rather than a critical section, so enabling it cannot select std.
+facade = ["dep:log"]
+
+[dependencies]
+kaptan-log-derive = { path = "../kaptan-log-derive" }
+log = { version = "0.4.33", default-features = false, optional = true }