feat: triple-toggle CPU display mode via 1 key; add tooltip, font, hit-test

CPU display now cycles through three states with each press of 1:
  0 = CPUModeAverage  – aggregate bar only (default)
  1 = CPUModeCores    – individual core bars + aggregate
  2 = CPUModeOff      – all CPU bars hidden

Config file stores cpumode=N (integer); old showcores=0/1 is read for
backward compatibility. CLI flag --showcores replaced by --cpumode.

Other improvements landed in this commit:
- internal/display: add font.go (text rendering), hittest.go (bar hit
  testing), tooltip.go (mouse-over tooltip), tooltip_test.go
- internal/display: mouse tracking and drawOverlay hook in display.go
- internal/display: update build tags to //go:build form
- internal/collector: embed remote script via script_embed.go /
  scriptdata/loadbars-remote.sh
- internal/collector: CPULine.Total() changed to value receiver
- internal/collector: table test improvements (name field, t.Run)
- internal/constants: BytesPerSec consts promoted from var to const
- Magefile.go: fix error formatting and install path

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

1 files changed, 3 insertions, 6 deletions

diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 630fa47..7b0bb37 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -25,9 +25,6 @@ func TestConfig_parseReader(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			c := Default()
-			f, _ := os.Open(os.DevNull)
-			defer f.Close()
-			// Use a temp file with the content since parseReader takes *os.File
 			dir := t.TempDir()
 			path := filepath.Join(dir, "rc")
 			if err := os.WriteFile(path, []byte(tt.input), 0600); err != nil {
@@ -54,7 +51,7 @@ func TestConfig_parseReader(t *testing.T) {
 func TestConfig_writeTo(t *testing.T) {
 	c := Default()
 	c.BarWidth = 25
-	c.ShowCores = true
+	c.CPUMode = 1 // CPUModeCores
 	dir := t.TempDir()
 	path := filepath.Join(dir, "out")
 	f, err := os.Create(path)
@@ -73,8 +70,8 @@ func TestConfig_writeTo(t *testing.T) {
 	if !bytes.Contains(data, []byte("barwidth=25")) {
 		t.Errorf("expected barwidth=25 in %s", data)
 	}
-	if !bytes.Contains(data, []byte("showcores=1")) {
-		t.Errorf("expected showcores=1 in %s", data)
+	if !bytes.Contains(data, []byte("cpumode=1")) {
+		t.Errorf("expected cpumode=1 in %s", data)
 	}
 }