[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/notifications.jsonc

@@ -0,0 +1,29 @@
+    "custom/notifications": {
+        "format": "{icon} {}",
+        "rotate": ${r_deg},
+        "format-icons": {
+            "email-notification": "<span foreground='white'><sup></sup></span>",
+            "chat-notification": "󱋊<span foreground='white'><sup></sup></span>",
+            "warning-notification": "󱨪<span foreground='yellow'><sup></sup></span>",
+            "error-notification": "󱨪<span foreground='red'><sup></sup></span>",
+            "network-notification": "󱂇<span foreground='white'><sup></sup></span>",
+            "battery-notification": "󰁺<span foreground='white'><sup></sup></span>",
+            "update-notification": "󰚰<span foreground='white'><sup></sup></span>",
+            "music-notification": "󰝚<span foreground='white'><sup></sup></span>",
+            "volume-notification": "󰕿<span foreground='white'><sup></sup></span>",
+            "notification": "<span foreground='white'><sup></sup></span>",
+            "dnd": "",
+            "none": ""
+        },
+        "return-type": "json",
+        "exec-if": "which dunstctl",
+        "exec": "notifications.py",
+        "on-scroll-down": "sleep 0.1 && dunstctl history-pop",
+        "on-click": "dunstctl set-paused toggle",
+        "on-click-middle": "dunstctl history-clear",
+        "on-click-right": "dunstctl close-all",
+        "interval": 1,
+        "tooltip": true,
+        "escape": true
+    },
+