feat: define clean architecture layers and ports

src/application/ports/auth-session-port.js

@@ -0,0 +1,16 @@
+/**
+ * @typedef {"authenticated" | "unauthenticated" | "recovery-pending" | "integration-failed"} SessionState
+ */
+
+/**
+ * The session is opaque: credentials are attached without exposing tokens.
+ *
+ * @typedef {{
+ *   getState(): SessionState,
+ *   attach(request: Request): Promise<Request>,
+ *   recover(): Promise<"restored" | "no-session">,
+ *   onUnauthenticated(): void
+ * }} AuthSessionPort
+ */
+
+export {};