test(fifa17): make economy integration harness deterministic

Serialize Core access with a single pooled connection (the harness drives Core
sequentially via the blocking client) to avoid a WAL-mode-establishment race
across connections warming up on a brand-new DB file, and raise the readiness
ceiling for heavy parallel test-binary load. 10/10 deterministic. (Fixed
alongside a real Core robustness fix: per-connection pragmas + busy_timeout,
core 0360135.)

openfut-utas-host/tests/economy_integration.rs

@@ -21,7 +21,12 @@ use serde_json::{json, Value};
 /// Boot a Core instance against `db_url`, serving on an ephemeral port. Returns
 /// the serve task handle and its base URL.
 async fn start_core(db_url: &str) -> (tokio::task::JoinHandle<()>, String) {
-    let pool = openfut_core::db::init_pool(db_url, 5)
+    // One pooled connection: the harness drives Core sequentially (blocking
+    // client), so a single connection serializes access deterministically and
+    // avoids a WAL-mode-establishment race across connections warming up on a
+    // brand-new DB file. (Steady-state multi-connection concurrency is a
+    // separate, deferred requirement.)
+    let pool = openfut_core::db::init_pool(db_url, 1)
         .await
         .expect("core pool");
     openfut_core::db::run_migrations(&pool)
@@ -43,7 +48,10 @@ async fn start_core(db_url: &str) -> (tokio::task::JoinHandle<()>, String) {
 
 fn wait_ready(base: &str) {
     let http = reqwest::blocking::Client::new();
-    for _ in 0..100 {
+    // Generous ceiling (~30s): returns on first success, so it only ever waits
+    // this long if Core genuinely never comes up. Under heavy parallel test-binary
+    // load Core's content load (CardDb::load) can take several seconds to be ready.
+    for _ in 0..1500 {
         if let Ok(r) = http.get(format!("{base}/health")).send() {
             if r.status().is_success() {
                 return;