add: stripe integration

crates/core/src/model/auth.rs

@@ -40,6 +40,9 @@ pub struct User {
     /// External service connection details.
     #[serde(default)]
     pub connections: UserConnections,
+    /// The user's Stripe customer ID.
+    #[serde(default)]
+    pub stripe_id: String,
 }
 
 pub type UserConnections =
@@ -245,6 +248,7 @@ impl User {
             post_count: 0,
             request_count: 0,
             connections: HashMap::new(),
+            stripe_id: String::new(),
         }
     }