[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/modules/cava.jsonc

@@ -0,0 +1,24 @@
+{
+	"cava": {
+		// "cava_config": "$XDG_CONFIG_HOME/cava/cava.conf",
+		"framerate": 30,
+		"autosens": 1,
+		"sensitivity": 100,
+		"bars": 14,
+		"lower_cutoff_freq": 50,
+		"higher_cutoff_freq": 10000,
+		"method": "pulse",
+		"source": "auto",
+		"stereo": true,
+		"reverse": false,
+		"bar_delimiter": 0,
+		"monstercat": false,
+		"waves": false,
+		"noise_reduction": 0.77,
+		"input_delay": 2,
+		"format-icons": ["▁", "▂", "▃", "▄", "▅", "▆", "▇", "█"],
+		"actions": {
+			"on-click-right": "mode"
+		}
+	}
+}