fix: slider max value = available disk space, partition size input now editable

- slider maximum value calculated as disk size minus used partitions
- editing mode includes current partition capacity in available space
- size text input now writes back to add_size_str
- formatted MB label shown next to text input
- CHANGELOG.md updated

locales/en.toml

@@ -268,6 +268,9 @@ mp_select_hint = "Select…"
 mp_add_btn = "✓ Add"
 mp_size_hint = "Size (MB, 0=remaining):"
 mp_delete_confirm_yes = "✓ Yes, Delete"
+mp_new_partition         = "New Partition"
+mp_edit_partition        = "Edit"
+mp_save                  = "✓ Save"
 plan_root_suffix = " (root)"
 disk_min_required = "  ↳ %{err} (min. %{n} GB required)"
 

locales/tr.toml

@@ -240,6 +240,9 @@ mp_select_hint = "Seç…"
 mp_add_btn = "✓ Ekle"
 mp_size_hint = "Boyut (MB, 0=kalan):"
 mp_delete_confirm_yes = "✓ Evet, Sil"
+mp_new_partition         = "Yeni Bölüm"
+mp_edit_partition        = "Düzenle"
+mp_save                  = "✓ Kaydet"
 plan_root_suffix = " (kök)"
 disk_min_required = "  ↳ %{err} (min. %{n} GB gerekli)"