[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)

lw/.config/hypr/hyprlock-host.conf

@@ -0,0 +1,21 @@
+# lw hyprlock sizes — 1920x1080, scale 1.
+#
+# gui/.config/hypr/hyprlock.conf ships sizes tuned for wm's 3072x1728 logical panel; these
+# are those values × 0.625, which keeps the same proportions the layout was designed around
+# (clock ~13% of screen height, date ~2.5%, meta ~1.5%, logo ~16%).
+#
+# Caveat — lw is multi-monitor and hyprlock draws on every output. monitors.conf makes
+# $mainScreen (eDP-1) 1366x768, so on the built-in panel these read ~40% larger than
+# intended (clock ≈ 18% of its height). Sized for the 1920x1080 externals on purpose; if
+# the laptop panel is the one you actually lock on, use the 768-tuned set instead:
+#   $fsClock = 98  $fsDate = 20  $fsMeta = 12  $fsSmall = 11  $fsIcon = 18  $logoSize = 124
+$fsClock = 138
+$fsDate = 28
+$fsMeta = 16
+$fsSmall = 15
+$fsIcon = 25
+$logoSize = 175
+
+# No $y* overrides: the shared offsets in hyprlock.conf already spread the content to the
+# edges, and they land the same on both hosts because each host's sizes are the same
+# proportion of its screen. Override them here if lw ever needs to differ.