test(ios): use_modular_headers! for legacy pods after dropping useFrameworks

Without useFrameworks:static, old Obj-C pods (react-native-udp -> <React/RCTAssert.h>) lose the React umbrella header. use_modular_headers! restores module header maps so <React/...> resolves for udp and any other legacy pod, in one shot. SwiftUICore already gone (build #5). udp is abandoned (4.1.7, 2023) with no drop-in replacement, so patching headers beats replacing it. [unsigned: GPG]

app.json

@@ -131,6 +131,7 @@
       ],
       "expo-web-browser",
       ["./plugins/with-runtime-framework-headers.js"],
+      ["./plugins/withModularHeaders.js"],
       ["./plugins/withChangeNativeAndroidTextToWhite.js"],
       ["./plugins/withAndroidAlertColors.js"],
       ["./plugins/withAndroidManifest.js"],

plugins/withModularHeaders.js

@@ -0,0 +1,24 @@
+const { withPodfile } = require("expo/config-plugins");
+
+// Without `useFrameworks: static`, older Obj-C pods that do `#import <React/...>`
+// (e.g. react-native-udp's UdpSockets.m -> <React/RCTAssert.h>) can't resolve the
+// React umbrella. `use_modular_headers!` restores module-style header maps for all
+// pods so <React/...> resolves again. Inserted at the top of the main target.
+const MARKER = "use_modular_headers! # streamyfin: <React/...> for legacy pods";
+
+module.exports = function withModularHeaders(config) {
+  return withPodfile(config, (config) => {
+    let podfile = config.modResults.contents;
+
+    if (!podfile.includes(MARKER)) {
+      podfile = podfile.replace(
+        /^(target\s+['"][^'"]+['"]\s+do)\s*$/m,
+        (match) => `${match}\n  ${MARKER}`,
+      );
+      config.modResults.contents = podfile;
+      console.log("✅  withModularHeaders: use_modular_headers! injected");
+    }
+
+    return config;
+  });
+};