feat: add Go password session lifecycle

contracts/auth/logout-v1.json

@@ -0,0 +1,10 @@
+{
+  "version": 1,
+  "path": "/api/auth/logout",
+  "methods": ["GET", "POST"],
+  "status": 307,
+  "location": "https://app.example.test/auth/login?loggedOut=1",
+  "requiresAuthentication": false,
+  "cookieFixture": "session-cookie-v1.json",
+  "duplicateBaseCookieWrite": false
+}