Add shared OAuth flows

crates/aether-oauth/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "aether-oauth"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+description = "Shared OAuth abstractions for Aether identity and provider account flows"
+
+[dependencies]
+aether-contracts.workspace = true
+async-trait.workspace = true
+base64.workspace = true
+http.workspace = true
+reqwest.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+sha2.workspace = true
+thiserror.workspace = true
+url.workspace = true
+uuid.workspace = true
+
+[dev-dependencies]
+tokio.workspace = true