feat: add axum HTTP layer with lookup endpoint and healthz

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/server/Cargo.toml

@@ -6,14 +6,17 @@ authors.workspace = true
 
 [dependencies]
 async-trait = "0.1"
+axum = "0.8"
 futures = "0.3"
 moka = { version = "0.12", features = ["future"] }
 reqwest = "0.13"
 serde = { version = "1", features = ["derive"] }
+serde_json = "1"
 thiserror = "2"
 tokio = { version = "1", features = ["full"] }
 tracing = "0.1"
 wasmtime = { version = "45", features = ["component-model"] }
 
 [dev-dependencies]
-serde_json = "1"
+http-body-util = "0.1"
+tower = { version = "0.5", features = ["util"] }