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, 35 insertions, 0 deletions

diff --git a/internal/collector/scriptdata/loadbars-remote.sh b/internal/collector/scriptdata/loadbars-remote.sh
new file mode 100644
index 0000000..9037ad8
--- /dev/null
+++ b/internal/collector/scriptdata/loadbars-remote.sh
@@ -0,0 +1,35 @@
+#!/bin/bash
+# loadbars-remote.sh - Emits loadbars protocol (M LOADAVG, M MEMSTATS, M NETSTATS, M CPUSTATS)
+# for local or remote execution. No Perl required.
+# Usage: bash loadbars-remote.sh
+# Interval for CPU sampling (seconds)
+INTERVAL=0.14
+
+while true; do
+  # Load average: first 3 fields of /proc/loadavg joined by ;
+  echo "M LOADAVG"
+  read -r l1 l5 l15 _ < /proc/loadavg 2>/dev/null || true
+  echo "${l1:-0};${l5:-0};${l15:-0}"
+
+  # Memory: full /proc/meminfo
+  echo "M MEMSTATS"
+  cat /proc/meminfo 2>/dev/null || true
+
+  # Network: /proc/net/dev, skip 2 header lines, then "iface: rx... tx..."
+  echo "M NETSTATS"
+  while IFS= read -r line; do
+    line="${line/:/ }"
+    set -- $line
+    # $1=iface, $2=rx_bytes $3=rx_packets $4=rx_errs $5=rx_drop ... $10=tx_bytes $11=tx_packets $12=tx_errs $13=tx_drop
+    if [ -n "$2" ] || [ -n "${10:-}" ]; then
+      echo "$1:b=${2:-0};tb=${10:-0};p=${3:-0};tp=${11:-0} e=${4:-0};te=${12:-0};d=${5:-0};td=${13:-0}"
+    fi
+  done < <(tail -n +3 /proc/net/dev 2>/dev/null)
+
+  # CPU: /proc/stat, 20 times with INTERVAL sleep
+  echo "M CPUSTATS"
+  for _ in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
+    cat /proc/stat 2>/dev/null || true
+    sleep "$INTERVAL" 2>/dev/null || true
+  done
+done