feat: ctrl+t cycles to next theme globally

Uses existing theme.Next() to rotate through all built-in themes.
Shown in footer ShortHelp and documented in Help page.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: gitcoder89431

internal/app/keys.go

@@ -13,6 +13,7 @@ type KeyMap struct {
 	Quit          key.Binding
 	ForceQuit     key.Binding
 	Commands      key.Binding
+	NextTheme     key.Binding
 	Help          key.Binding
 	Cancel        key.Binding
 	Focus         key.Binding
@@ -27,6 +28,7 @@ func DefaultKeyMap() KeyMap {
 		Quit:          key.NewBinding(key.WithKeys("q"), key.WithHelp("q", "quit")),
 		ForceQuit:     key.NewBinding(key.WithKeys("ctrl+c"), key.WithHelp("ctrl+c", "quit")),
 		Commands:      key.NewBinding(key.WithKeys("ctrl+k"), key.WithHelp("ctrl+k", "commands")),
+		NextTheme:     key.NewBinding(key.WithKeys("ctrl+t"), key.WithHelp("ctrl+t", "next theme")),
 		Help:          key.NewBinding(key.WithKeys("?"), key.WithHelp("?", "help")),
 		Cancel:        key.NewBinding(key.WithKeys("esc"), key.WithHelp("esc", "close")),
 		Focus:         key.NewBinding(key.WithKeys("tab"), key.WithHelp("tab", "focus")),
@@ -38,9 +40,9 @@ func DefaultKeyMap() KeyMap {
 }
 
 func (k KeyMap) ShortHelp() []key.Binding {
-	return []key.Binding{k.Help, k.Commands, k.Quit}
+	return []key.Binding{k.Help, k.Commands, k.NextTheme, k.Quit}
 }
 
 func (k KeyMap) FullHelp() [][]key.Binding {
-	return [][]key.Binding{{k.Help, k.Commands, k.Focus, k.Cancel}, {k.Up, k.Down, k.Enter, k.ToggleSidebar, k.Quit, k.ForceQuit}}
+	return [][]key.Binding{{k.Help, k.Commands, k.NextTheme, k.Focus, k.Cancel}, {k.Up, k.Down, k.Enter, k.ToggleSidebar, k.Quit, k.ForceQuit}}
 }

internal/app/update.go

@@ -164,6 +164,10 @@ func (m Model) handleKey(msg tea.KeyPressMsg) (tea.Model, tea.Cmd) {
 		m.showCommandPalette = true
 		m.commandPalette.Reset(m.theme.Name, m.paletteContext())
 		return m, nil
+	case key.Matches(msg, m.keys.NextTheme):
+		m.theme = theme.Next(m.theme.Name)
+		m.updateDerivedScreens()
+		return m, nil
 	case key.Matches(msg, m.keys.Help):
 		m.showHelp = true
 		return m, nil

internal/screens/help.go

@@ -59,6 +59,7 @@ func (h Help) View(width, height int) string {
 
 	b.WriteString("\n" + rule("Command Palette") + "\n\n")
 	b.WriteString(binding("ctrl+k", "open palette"))
+	b.WriteString(binding("ctrl+t", "cycle to next theme"))
 	b.WriteString(binding("type", "filter commands"))
 	b.WriteString(binding("enter", "run selected command"))
 	b.WriteString(binding("esc", "close palette"))