[Sync] replace the flat layout with the unified stow tree

Supersedes the old flat .config/ layout (last published 2026-06-28) with the
private repo's structure: one shared base plus per-host overlays.

- packages: common/ gui/ lw/ fl/ wm/ plus install.sh and bin/ tooling
  (dotsync, reconcile-hyde.sh)
- new README covering the layout, deploy order and the HyDE dependency
- current HyDE waybar rig (layouts/, cava), pi agent extensions, claude/
  config, tmux, presenterm, aichat roles
- fish: kp (keepassxc-cli + fzf picker, db path from $KP_DB) and
  bind_M_n_history (alt+1..9 recalls the nth history entry)
- drops cruft that should never have been tracked: the duplicate top-level
  .pi/ copy, btop.log, zellij config.kdl.bak, fish_variables
- .pi/agent/auth.json is gitignored; auth.json.example ships instead

Host-specific work sessions and the personal backlog stay in the private
tree. Endpoint locators in the llamacpp/whisper guides are placeholders
($SERVER, <own-domain>) — the guides themselves stay, since they are the
useful part.

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"
+		}
+	}
+}