fix(ui): spartito ad altezza fissa con auto-scroll; inserimento manuale segue l'ultima nota

- StaffFullView: viewport limitato (maxVisibleHeight, default 340dp) con
  scroll interno — in Pratica la card della nota rilevata resta sempre
  visibile anche con spartiti lunghi; l'auto-scroll alla riga corrente
  ora ha un viewport reale su cui agire
- ManualInputScreen: la riga delle note selezionate scorre da sola
  sull'ultima nota inserita

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

shared/src/commonMain/kotlin/com/notemusicali/ui/components/StaffFullView.kt

@@ -1,6 +1,7 @@
 package com.notemusicali.ui.components
 
 import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxWithConstraints
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
@@ -13,6 +14,7 @@ import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.rememberTextMeasurer
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.notemusicali.music.MusicalNote
 
@@ -29,6 +31,8 @@ fun StaffFullView(
     lightTheme: Boolean = false,
     beats: Int = 4,
     beatType: Int = 4,
+    // Altezza massima visibile: oltre, lo spartito scorre da solo seguendo la nota corrente
+    maxVisibleHeight: Dp = 340.dp,
 ) {
     if (notes.isEmpty()) return
 
@@ -65,12 +69,18 @@ fun StaffFullView(
             scrollState.animateScrollTo(targetY)
         }
 
-        Canvas(
+        val viewportHeightDp = if (totalHeightDp < maxVisibleHeight) totalHeightDp else maxVisibleHeight
+        Box(
             modifier = Modifier
                 .fillMaxWidth()
-                .verticalScroll(scrollState)
+                .height(viewportHeightDp)
-                .height(totalHeightDp),
+                .verticalScroll(scrollState),
         ) {
+            Canvas(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .height(totalHeightDp),
+            ) {
             val lineColor = if (lightTheme) Color.Black else Color.White.copy(alpha = 0.4f)
             val dimColor = if (lightTheme) Color.Black else Color.White.copy(alpha = 0.35f)
             val playedColor = if (lightTheme) Color.Black.copy(alpha = 0.35f) else Color.White.copy(alpha = 0.2f)
@@ -194,5 +204,6 @@ fun StaffFullView(
                 }
             }
         }
+        }
     }
 }

shared/src/commonMain/kotlin/com/notemusicali/ui/practice/ManualInputScreen.kt

@@ -21,6 +21,8 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.layout.widthIn
+import androidx.compose.foundation.lazy.rememberLazyListState
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.foundation.lazy.LazyRow
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.rememberScrollState
@@ -231,7 +233,13 @@ fun ManualInputScreen(
             )
 
             if (notes.isNotEmpty()) {
+                val notesRowState = rememberLazyListState()
+                LaunchedEffect(notes.size) {
+                    // Segui sempre l'ultima nota inserita
+                    notesRowState.animateScrollToItem(notes.size - 1)
+                }
                 LazyRow(
+                    state = notesRowState,
                     horizontalArrangement = Arrangement.spacedBy(6.dp),
                     modifier = Modifier
                         .fillMaxWidth()