[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/alacritty/theme.toml

@@ -0,0 +1,33 @@
+# Synthwave '84 — matches ../kitty/theme.conf
+
+[colors.primary]
+background = "#262335"
+foreground = "#ffffff"
+
+[colors.cursor]
+text = "#262335"
+cursor = "#f97e72"
+
+[colors.selection]
+text = "#262335"
+background = "#f97e72"
+
+[colors.normal]
+black = "#232530"
+red = "#fe4450"
+green = "#72f1b8"
+yellow = "#ff7edb"
+blue = "#03edf9"
+magenta = "#fede5d"
+cyan = "#03edf9"
+white = "#ffffff"
+
+[colors.bright]
+black = "#232530"
+red = "#fe4450"
+green = "#72f1b8"
+yellow = "#ff7edb"
+blue = "#03edf9"
+magenta = "#f3e70f"
+cyan = "#03edf9"
+white = "#ffffff"