Initial commit: InTono — app KMP per l'apprendimento musicale

App Kotlin Multiplatform (Android/iOS/Desktop) con Compose Multiplatform:
controllo intonazione (YIN), pratica guidata, metronomo, ear training,
sfide, scansione spartiti via AI, spartiti bundled e pentagramma con
glifi tipografici, travature, battute e spaziatura proporzionale.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

shared/src/androidMain/kotlin/com/notemusicali/ui/components/FilePicker.android.kt

@@ -0,0 +1,35 @@
+package com.notemusicali.ui.components
+
+import android.net.Uri
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.platform.LocalContext
+import com.notemusicali.scores.extractMusicXmlFromBytes
+
+@Composable
+actual fun rememberFilePickerLauncher(
+    mimeTypes: List<String>,
+    onFileContent: (String) -> Unit,
+): () -> Unit {
+    val context = LocalContext.current
+    val launcher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.OpenDocument()
+    ) { uri: Uri? ->
+        uri?.let {
+            try {
+                context.contentResolver.openInputStream(it)?.use { stream ->
+                    val bytes = stream.readBytes()
+                    val content = extractMusicXmlFromBytes(bytes)
+                    if (content != null) {
+                        onFileContent(content)
+                    }
+                }
+            } catch (_: Exception) {
+                // File read failed
+            }
+        }
+    }
+
+    return { launcher.launch(mimeTypes.toTypedArray()) }
+}