fix(viewport): Reset cursor position when changing file list

Adds explicit cursor and viewport reset logic when the file list
changes due to searching, filtering, or refreshing. This ensures the
cursor is always at a valid position and the viewport shows from the
top of the list when:
- Exiting search mode
- Refreshing the file list
- Toggling gitignore filters
- Toggling hidden file display
- Starting a new search

Author: epilande

internal/model/init_update.go

@@ -141,6 +141,8 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 				m.searchInput.Blur()
 				m.searchInput.SetValue("")
 				m.searchResults = nil
+				m.cursor = 0
+				m.viewport.GotoTop()
 				m.collapseAllDirectories()
 				m.refreshViewportContent()
 				return m, nil
@@ -200,6 +202,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.deselected = make(map[string]bool)
 			m.isDependency = make(map[string]bool)
 			m.cursor = 0
+			m.viewport.GotoTop()
 			return m, tea.Sequence(
 				m.reloadFiles(),
 				func() tea.Msg { return refreshMsg{} },
@@ -257,6 +260,8 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.searchInput.Focus()
 			m.searchInput.SetValue("")
 			m.searchResults = nil
+			m.cursor = 0
+			m.viewport.GotoTop()
 			m.expandAllDirectories()
 			m.refreshViewportContent()
 			return m, nil
@@ -278,11 +283,15 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.useGitIgnore = !m.useGitIgnore
 			m.generator.UseGitIgnore = m.useGitIgnore
 			m.filterSelections()
+			m.cursor = 0
+			m.viewport.GotoTop()
 			return m, m.reloadFiles()
 		case ".":
 			m.showHidden = !m.showHidden
 			m.generator.ShowHidden = m.showHidden
 			m.filterSelections()
+			m.cursor = 0
+			m.viewport.GotoTop()
 			return m, m.reloadFiles()
 		case "D":
 			m.resolveDeps = !m.resolveDeps