[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/waybar/modules/clock.jsonc

@@ -0,0 +1,25 @@
+    "clock": {
+        "format": "{:%H:%M}",
+        "rotate": ${r_deg},
+        "format-alt": "{:%R 󰃭 %d·%m·%y}",
+        "tooltip-format": "<span>{calendar}</span>",
+        "calendar": {
+            "mode": "month",
+            "mode-mon-col": 3,
+            "on-scroll": 1,
+            "on-click-right": "mode",
+            "format": {
+                "months": "<span color='#ffead3'><b>{}</b></span>",
+                "weekdays": "<span color='#ffcc66'><b>{}</b></span>",
+                "today": "<span color='#ff6699'><b>{}</b></span>"
+            }
+        },
+        "actions": {
+            "on-click-right": "mode",
+            "on-click-forward": "tz_up",
+            "on-click-backward": "tz_down",
+            "on-scroll-up": "shift_up",
+            "on-scroll-down": "shift_down"
+        }
+    },
+