feat: add navigation and window size handlers with corresponding tests

internal/handlers/winSizeMsgHandler.go

@@ -0,0 +1,17 @@
+package handlers
+
+import (
+	"github.com/StevanFreeborn/term-tier/internal/state"
+	tea "github.com/charmbracelet/bubbletea"
+)
+
+type WinSizeMsgHandler interface {
+	Match(s state.State, msg tea.WindowSizeMsg) bool
+	Handle(s state.State, msg tea.WindowSizeMsg) tea.Cmd
+}
+
+func GetAllWinSizeHandlers() []WinSizeMsgHandler {
+	return []WinSizeMsgHandler{
+		NewTrackWindowSizeHandler(),
+	}
+}