[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.

lw/.config/xremap/config.yml

@@ -0,0 +1,40 @@
+# F13 is a real keycode that no app binds. We declare it a virtual modifier so it can
+# prefix the nav-layer chords below, then remap RightAlt -> F13 (see modmap). This mirrors
+# the wm/fl evremap setup: RightAlt only ever emits F13, so a bare tap/hold never triggers
+# app menu bars and no stray Alt leaks on unmapped chords.
+virtual_modifiers:
+  - F13
+
+modmap:
+  - name: CapsLock to LeftCtrl/Esc
+    remap:
+      CapsLock:
+        held: leftctrl
+        alone: esc
+        alone_timeout_millis: 150
+
+  - name: RightAlt to F13 (nav-layer modifier; Left Alt untouched)
+    remap:
+      Alt_R: F13
+
+keymap:
+  - name: RightAlt(F13) vim-nav layer — mirrors wm/fl evremap
+    remap:
+      F13-h: left
+      F13-j: down
+      F13-k: up
+      F13-l: right
+      F13-u: pageup
+      F13-d: pagedown
+      F13-b: C-left      # word left  (Ctrl+Left)
+      F13-w: C-right     # word right (Ctrl+Right)
+
+# keymap:
+#   - name: Freetube remap
+#     application:
+#       only: FreeTube
+#     remap:
+#       Alt-h: Left
+#       Alt-l: Right
+#       Alt-j: Down
+#       Alt-k: Up