[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/bluetooth.jsonc

@@ -0,0 +1,15 @@
+    "bluetooth": {
+        "format": "",
+        "rotate": ${r_deg},
+        "format-disabled": "",
+        "format-connected": " {num_connections}",
+        "format-connected-battery": "{icon} {num_connections}",
+        // "format-connected-battery": "{icon} {device_alias}-{device_battery_percentage}%",
+        "format-icons": ["󰥇", "󰤾", "󰤿", "󰥀", "󰥁", "󰥂", "󰥃", "󰥄", "󰥅", "󰥆", "󰥈"],
+        // "format-device-preference": [ "device1", "device2" ], // preference list deciding the displayed device If this config option is not defined or none of the devices in the list are connected, it will fall back to showing the last connected device.
+        "tooltip-format": "{controller_alias}\n{num_connections} connected",
+        "tooltip-format-connected": "{controller_alias}\n{num_connections} connected\n\n{device_enumerate}",
+        "tooltip-format-enumerate-connected": "{device_alias}",
+        "tooltip-format-enumerate-connected-battery": "{device_alias}\t{icon} {device_battery_percentage}%"
+    },
+