chore: replace placeholder package with role-named workspace

crates/api/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "api"
+version = "0.0.0"
+edition.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+axum.workspace = true
+serde.workspace = true
+utoipa.workspace = true
+db = { path = "../db" }
+
+[dev-dependencies]
+tokio.workspace = true
+tower.workspace = true
+http-body-util.workspace = true
+serde_json.workspace = true
+sqlx.workspace = true

crates/api/src/lib.rs

@@ -0,0 +1 @@
+//! HTTP API: router, handlers, and OpenAPI document.