feat: unify recommend anonymous runtime guest auth

- Route recommended runtime launches through shared runtime guest token handling
- Extend recommend-page anonymous play beyond jump-hop
- Add regression coverage for runtime guest launch clients
- Update docs to reflect the full anonymous-play matrix

server-rs/crates/shared-contracts/src/auth.rs

@@ -42,6 +42,15 @@ pub struct PublicUserSearchResponse {
     pub user: PublicUserSummaryPayload,
 }
 
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct RuntimeGuestTokenResponse {
+    pub token: String,
+    pub expires_at: String,
+    pub subject: String,
+    pub scope: String,
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct PasswordEntryRequest {