[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/kitty/music.conf

@@ -0,0 +1,20 @@
+# run with `kitty --session ~/.config/kitty/music.conf`
+
+# os_window_size 220c 64c
+# create a new tab
+new_tab music
+layout splits
+
+# set the working directory for windows in the current tab
+cd ~
+
+# Splits are sized with --bias (a percentage of the space being split) rather
+# than `resize_window taller/wider N`: that takes N *cells*, so on a small window
+# N swamps the available space and the other pane collapses to nothing -- cava
+# was disappearing. --bias keeps the same proportions at any window size.
+# Tune: --bias here is the share the *new* pane takes; cava gets the remainder.
+launch --var window=first cava
+# create additional terminals
+launch --location=hsplit --bias 80 pyradio
+focus
+launch --location=vsplit --bias 65 pipes-rs