feat(FN-1754): raise global max concurrent ceiling to 10000

- Enforce 10000 upper bound in CentralCore for globalMaxConcurrent setting
- Add 10000 upper bound validation in the project settings API route
- Raise max ceiling in SettingsModal from previous limit to 10000
- Add route test verifying the 10000 upper bound is enforced

packages/dashboard/app/components/SettingsModal.tsx

@@ -1545,7 +1545,7 @@ export function SettingsModal({
                 id="globalMaxConcurrent"
                 type="number"
                 min={1}
-                max={50}
+                max={10000}
                 value={globalMaxConcurrent ?? ""}
                 onChange={(e) => {
                   const val = e.target.value;