fix(tui): address PR #27 remaining review items

- Replace handledCmd nil-returning goroutine with pre-allocated
  handledNoop Msg to avoid per-call goroutine allocation
- Extract mouse scroll step magic number 3 to mouseScrollStep
  constant (reuse existing definition from column.go)

Author: engalar

cmd/mxcli/tui/app.go

@@ -14,10 +14,13 @@ import (
 // chromeHeight is the vertical space consumed by tab bar (1) + hint bar (1) + status bar (1).
 const chromeHeight = 3
 
+// handledNoop is a pre-allocated no-op Msg to avoid per-call goroutine allocation.
+var handledNoop tea.Msg = struct{}{}
+
 // handledCmd is returned by handleBrowserAppKeys to signal that a key was
 // consumed without producing a follow-up message.  Using a shared variable
 // avoids allocating a new closure on every handled keystroke.
-var handledCmd tea.Cmd = func() tea.Msg { return nil }
+var handledCmd tea.Cmd = func() tea.Msg { return handledNoop }
 
 // compareFlashClearMsg is sent 1 s after a clipboard copy in compare view.
 type compareFlashClearMsg struct{}

cmd/mxcli/tui/contentview.go

@@ -172,9 +172,9 @@ func (v ContentView) Update(msg tea.Msg) (ContentView, tea.Cmd) {
 		if msg.Action == tea.MouseActionPress {
 			switch msg.Button {
 			case tea.MouseButtonWheelUp:
-				v.yOffset = clamp(v.yOffset-3, 0, v.maxOffset())
+				v.yOffset = clamp(v.yOffset-mouseScrollStep, 0, v.maxOffset())
 			case tea.MouseButtonWheelDown:
-				v.yOffset = clamp(v.yOffset+3, 0, v.maxOffset())
+				v.yOffset = clamp(v.yOffset+mouseScrollStep, 0, v.maxOffset())
 			}
 		}
 	}