[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/kitty/kitty.conf

@@ -0,0 +1,21 @@
+include theme.conf
+
+font_size 12.0
+font_family      CaskaydiaCove Nerd Font Mono
+bold_font        auto
+italic_font      auto
+bold_italic_font auto
+window_padding_width 25
+enable_audio_bell no
+cursor_trail 1
+cursor_blink_interval 0.4 ease-in-out
+
+tab_bar_style       powerline
+tab_powerline_style slanted
+
+confirm_os_window_close 0
+#background_opacity 0.60
+#hide_window_decorations yes
+
+# Per-host overrides (font_size, padding, opacity…) — included last so it wins.
+include host.conf