[Sync] adopt unified stow layout from the private repo

Mirrors the private dots tree at 900bdda: one shared base plus per-host
overlays, replacing the old flat .config/ layout (last synced 2026-06-28).

- packages: common/ gui/ wm/ lw/ fl/ + install.sh and bin/ tooling (dotsync,
  reconcile-hyde.sh)
- new README (layout, deploy order, HyDE dependency), plus ToDo.md and
  HYDE-UPDATE.md
- current HyDE waybar rig (layouts/, cava), pi agent extensions, claude/
  config, tmux, presenterm, aichat roles
- drops stale duplicates and generated cruft that should never have been
  tracked: the second top-level .pi/ copy, btop.log, zellij config.kdl.bak,
  fish_variables, nvim codecompanion.lua
- .pi/agent/auth.json is gitignored now; auth.json.example ships instead
- fl/ and wm/ hypr themes/ stay untracked (HyDE-generated per machine, per
  the root .gitignore)

gui/.config/waybar/cava-waybar.sh

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+# Self-contained waybar cava module: stream `cava` raw output as Unicode bar chars.
+# No HyDE dependency — just needs `cava` installed. Usage: cava-waybar.sh [bars]
+#   bars = number of columns (even; ~screen_px / (font-size * 0.6)); default 94.
+#
+# waybar's custom/cava module uses restart-interval, so this script is relaunched
+# every time it exits. Without cleanup each relaunch would leak an orphaned `cava`
+# child and they'd pile up. We enforce a single instance: track cava's own PID,
+# kill it on exit, and reap any stale instance left by a previous (crashed) run.
+bars="${1:-94}"
+chars="▁▂▃▄▅▆▇█"   # cava ascii value 0..7 -> these
+
+conf="$(mktemp)"
+pidfile="${XDG_RUNTIME_DIR:-/tmp}/cava-waybar.pid"
+
+cava_pid=""
+cleanup() {
+  [[ -n "$cava_pid" ]] && kill "$cava_pid" 2>/dev/null
+  rm -f "$conf" "$pidfile"
+}
+trap cleanup EXIT INT TERM
+
+# Reap a stale cava from a previous run that didn't clean up (e.g. hard kill).
+if [[ -f "$pidfile" ]]; then
+  old="$(cat "$pidfile" 2>/dev/null)"
+  [[ "$old" =~ ^[0-9]+$ ]] && kill "$old" 2>/dev/null
+fi
+
+cat >"$conf" <<EOF
+[general]
+bars = $bars
+[output]
+method = raw
+raw_target = /dev/stdout
+data_format = ascii
+ascii_max_range = 7
+EOF
+
+# sed program: drop the ';' separators, then map each digit 0..7 to its bar char
+prog="s/;//g"
+for i in 0 1 2 3 4 5 6 7; do
+  prog+=";s/$i/${chars:$i:1}/g"
+done
+
+# Run cava in the background (not a `cava | sed` pipeline) so we hold its real PID
+# and can kill it in cleanup. stdbuf -oL line-buffers cava so waybar gets each frame
+# immediately (no choppy lag); its stdout is piped to sed via process substitution.
+stdbuf -oL cava -p "$conf" > >(sed -u "$prog") &
+cava_pid=$!
+echo "$cava_pid" >"$pidfile"
+wait "$cava_pid"