vim: add plugins, tmux: status bar, fix Ctrl+A clash

- Add vim-gitgutter, vim-commentary, vim-surround via install
script
- Rebind git log widget from Ctrl+A to Ctrl+T (tmux prefix
clash)
- Add date, time, and battery indicator to tmux status
bar
- Set tmux clock colour to teal

Co-authored-by: Copilot
<223556219+Copilot@users.noreply.github.com>

home/.tmux/battery.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Battery indicator for tmux status bar.
+# Shows percentage only when on battery; amber when <=20%.
+
+pct=""
+charging=""
+
+if command -v pmset &>/dev/null; then
+    # macOS
+    info=$(pmset -g batt)
+    pct=$(echo "$info" | grep -o '[0-9]\+%' | head -1 | tr -d '%')
+    echo "$info" | grep -q 'AC Power' && charging=1
+elif [[ -f /sys/class/power_supply/BAT0/capacity ]]; then
+    # Linux
+    pct=$(cat /sys/class/power_supply/BAT0/capacity)
+    status=$(cat /sys/class/power_supply/BAT0/status)
+    [[ "$status" == "Charging" || "$status" == "Full" ]] && charging=1
+fi
+
+[[ -z "$pct" ]] && exit 0
+
+if [[ -n "$charging" ]]; then
+    echo "#[fg=#808080]AC#[default]"
+elif (( pct <= 20 )); then
+    echo "#[fg=#f88c14,bold]${pct}%#[default]"
+else
+    echo "#[fg=#808080]${pct}%#[default]"
+fi