[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.

common/.config/cava/themes/solarized_dark

@@ -0,0 +1,15 @@
+[color]
+background = '#001e26'
+foreground = '#708183'
+
+gradient = 1
+gradient_color_1 = '#268bd2'
+gradient_color_2 = '#6c71c4'
+gradient_color_3 = '#cb4b16'
+
+horizontal_gradient = 1
+horizontal_gradient_color_1 = '#586e75'
+horizontal_gradient_color_2 = '#b58900'
+horizontal_gradient_color_3 = '#839496'
+
+blend_direction = 'up'

common/.config/cava/themes/tricolor

@@ -0,0 +1,10 @@
+[color]
+horizontal_gradient = 1
+horizontal_gradient_color_1 = '#c45161'
+horizontal_gradient_color_2 = '#e094a0'
+horizontal_gradient_color_3 = '#f2b6c0'
+horizontal_gradient_color_4 = '#f2dde1'
+horizontal_gradient_color_5 = '#cbc7d8'
+horizontal_gradient_color_6 = '#8db7d2'
+horizontal_gradient_color_7 = '#5e62a9'
+horizontal_gradient_color_8 = '#434279'