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, 82 insertions, 0 deletions

diff --git a/internal/display/hittest.go b/internal/display/hittest.go
new file mode 100644
index 0000000..fe88471
--- /dev/null
+++ b/internal/display/hittest.go
@@ -0,0 +1,82 @@
+package display
+
+import (
+	"codeberg.org/snonux/loadbars/internal/config"
+	"codeberg.org/snonux/loadbars/internal/stats"
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+// barKind identifies what type of data a bar represents.
+type barKind int
+
+const (
+	barCPU barKind = iota
+	barMem
+	barNet
+)
+
+// barDescriptor describes a single bar's position, host, and type.
+type barDescriptor struct {
+	host    string  // hostname this bar belongs to
+	kind    barKind // CPU, mem, or net
+	cpuName string  // CPU name (e.g. "cpu", "cpu0"); only set for barCPU
+	rect    sdl.Rect
+}
+
+// buildBarMap replays the same host/bar iteration as drawBars to produce
+// a slice of bar descriptors with their screen rectangles.
+func buildBarMap(snap map[string]*stats.HostStats, cfg *config.Config, state *runState) []barDescriptor {
+	numBars := countBars(snap, state.cpuMode, state.showMem, state.showNet)
+	maxPerRow := cfg.MaxBarsPerRow
+	hosts := sortedHosts(snap)
+
+	bars := make([]barDescriptor, 0, numBars)
+	barIndex := 0
+	for _, host := range hosts {
+		h := snap[host]
+		if h == nil {
+			continue
+		}
+		cpuNames := sortedCPUNames(h.CPU, state.cpuMode)
+		for _, name := range cpuNames {
+			x, y, w, bh := barRect(state.winW, state.winH, numBars, maxPerRow, barIndex)
+			bars = append(bars, barDescriptor{
+				host:    host,
+				kind:    barCPU,
+				cpuName: name,
+				rect:    sdl.Rect{X: x, Y: y, W: w, H: bh},
+			})
+			barIndex++
+		}
+		if state.showMem {
+			x, y, w, bh := barRect(state.winW, state.winH, numBars, maxPerRow, barIndex)
+			bars = append(bars, barDescriptor{
+				host: host,
+				kind: barMem,
+				rect: sdl.Rect{X: x, Y: y, W: w, H: bh},
+			})
+			barIndex++
+		}
+		if state.showNet {
+			x, y, w, bh := barRect(state.winW, state.winH, numBars, maxPerRow, barIndex)
+			bars = append(bars, barDescriptor{
+				host: host,
+				kind: barNet,
+				rect: sdl.Rect{X: x, Y: y, W: w, H: bh},
+			})
+			barIndex++
+		}
+	}
+	return bars
+}
+
+// hitTest returns the bar descriptor under the given point, or nil if none.
+func hitTest(bars []barDescriptor, mx, my int32) *barDescriptor {
+	for i := range bars {
+		r := &bars[i].rect
+		if mx >= r.X && mx < r.X+r.W && my >= r.Y && my < r.Y+r.H {
+			return &bars[i]
+		}
+	}
+	return nil
+}