[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)

common/.config/fish/functions/lk.fish

@@ -0,0 +1,18 @@
+function lk --description 'linux knowledge' 
+	set -l DB "$HOME/projects/dmz/soft/lk/db.rec"
+	set -l passes 0
+	set -l count 0
+	set -l query ""
+
+	while test $passes -lt 2; and test $count -eq 0
+		set query (recsel "$DB" -p aim,tag | recsel -iq "$query" -CP aim,tag | sort -u | fzf --preview="recsel \"$DB\" -e \"aim~{}\" | bat")
+		if test -n "$query"
+			set count (recsel "$DB" -q "$query" -c)
+		end
+		set passes (math $passes + 1)
+	end
+
+	if test $count -eq 1
+		recsel "$DB" -q "$query" | recfmt -f "$HOME/projects/dmz/soft/lk/lists.fmt" | less
+	end
+end