Add sleep tracking, statistics module and backup features

Features:
- Sleep tracking with timer and manual duration input
- Statistics module with 5 tabs (daily summary, feeding, diapers, sleep, growth)
- Export/Import backup functionality in settings
- Complete German, French and Italian translations

.gitignore

@@ -107,3 +107,5 @@ app/release/output-metadata.json
 # Other
 app/src/main/java/it/danieleverducci/lunatracker/TemporaryHardcodedCredentials.kt
 .kotlin/sessions/*
+CLAUDE.md
+.claude/

app/src/main/java/it/danieleverducci/lunatracker/MainActivity.kt

@@ -695,18 +695,12 @@ class MainActivity : AppCompatActivity() {
                 )
                 picker.minValue = 1
                 picker.maxValue = if (isSleep) 180 else 60
-                val oldQuantity = event.quantity
                 picker.value = if (event.quantity > 0) Math.min(event.quantity, picker.maxValue) else if (isSleep) 30 else 15
 
                 pickerDialog.setTitle(if (isSleep) R.string.sleep_duration_title else R.string.breastfeeding_duration_title)
                 pickerDialog.setView(pickerView)
                 pickerDialog.setPositiveButton(android.R.string.ok) { _, _ ->
-                    val newQuantity = picker.value
-                    if (newQuantity != oldQuantity) {
-                        // Adjust end time based on duration change (duration reduced = end time earlier)
-                        event.time = event.time - (oldQuantity - newQuantity) * 60L
-                        event.quantity = newQuantity
-                    }
+                    event.quantity = picker.value
                     quantityTextView.text = NumericUtils(this@MainActivity).formatEventQuantity(event)
                     recyclerView.adapter?.notifyDataSetChanged()
                     saveLogbook()