[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)

wm/.config/hypr/host.conf

@@ -0,0 +1,15 @@
+# wm host extras (sourced last by ~/.config/hypr/hyprland.conf)
+source = ~/.config/hypr/nvidia.conf
+
+# THEME OVERRIDES — personal deltas on top of wm's themes/theme.conf (tracked in this
+# overlay while wm's HyDE is old enough to hard-source it; that file is generated, so
+# anything edited in there is lost on the next theme switch — keep the deltas here,
+# where they are sourced after every theme file and therefore win).
+general {
+    gaps_in = 2
+    gaps_out = 4
+}
+
+decoration {
+    rounding = 8
+}