Add expo-keyboard-language native module

New Expo module that exposes keyboard language detection via a node
handle. On iOS it resolves the React Native view tag to the underlying
UITextField/UITextView and returns textInputMode.primaryLanguage (BCP 47
tag). Android and web return null for now.

https://claude.ai/code/session_01AMCp4M56WtFPz1pZtwgcvx

modules/expo-keyboard-language/android/src/main/AndroidManifest.xml

@@ -0,0 +1 @@
+<manifest/>

modules/expo-keyboard-language/android/src/main/java/expo/modules/keyboardlanguage/ExpoKeyboardLanguageModule.kt

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+package expo.modules.keyboardlanguage
+
+import expo.modules.kotlin.modules.Module
+import expo.modules.kotlin.modules.ModuleDefinition
+
+class ExpoKeyboardLanguageModule : Module() {
+  override fun definition() =
+    ModuleDefinition {
+      Name("ExpoKeyboardLanguage")
+
+      Function("getKeyboardLanguage") { _: Int ->
+        return@Function null as String?
+      }
+    }
+}