fix(ios): resolve Xcode 26 build failures with fmt consteval and icon sizing

Xcode 26's stricter Clang rejects consteval usage in the fmt library
bundled with hermes-engine, and enforces exact imagestack layer sizing
for tvOS app icons.

Author: giolaq

apps/expo-multi-tv/app.json

@@ -4,6 +4,7 @@
       "./plugins/withKotlinJvmTarget",
       "./plugins/withKeyEvent",
       "./plugins/withTvosDeploymentTarget",
+      "./plugins/withFmtXcode26Fix",
       [
         "@react-native-tvos/config-tv",
         {

apps/expo-multi-tv/assets/tv_icons/icon-400x240.png

@@ -0,0 +1,37 @@
+const { withDangerousMod } = require("expo/config-plugins");
+const fs = require("fs");
+const path = require("path");
+
+function withFmtXcode26Fix(config) {
+  return withDangerousMod(config, [
+    "ios",
+    (config) => {
+      const podfilePath = path.join(
+        config.modRequest.platformProjectRoot,
+        "Podfile"
+      );
+      let podfile = fs.readFileSync(podfilePath, "utf8");
+
+      const fmtFix = `
+    # Fix fmt consteval errors on Xcode 26+
+    installer.pods_project.targets.each do |target|
+      if target.name == 'fmt'
+        target.build_configurations.each do |config|
+          config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= ['$(inherited)']
+          config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] << 'FMT_CONSTEVAL=constexpr'
+        end
+      end
+    end`;
+
+      podfile = podfile.replace(
+        /post_install do \|installer\|/,
+        `post_install do |installer|${fmtFix}`
+      );
+
+      fs.writeFileSync(podfilePath, podfile, "utf8");
+      return config;
+    },
+  ]);
+}
+
+module.exports = withFmtXcode26Fix;