[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/claude/keybindings.json

@@ -0,0 +1,36 @@
+{
+  "$schema": "https://www.schemastore.org/claude-code-keybindings.json",
+  "$docs": "https://code.claude.com/docs/en/keybindings",
+  "bindings": [
+    {
+      "context": "Global",
+      "bindings": {
+        "alt+j": "scroll:lineDown",
+        "alt+k": "scroll:lineUp",
+        "ctrl+shift+j": "scroll:lineDown",
+        "ctrl+shift+k": "scroll:lineUp"
+      }
+    },
+    {
+      "context": "MessageSelector",
+      "bindings": {
+        "g": "messageSelector:top",
+        "shift+g": "messageSelector:bottom"
+      }
+    },
+    {
+      "context": "Select",
+      "bindings": {
+        "g": "select:first",
+        "shift+g": "select:last"
+      }
+    },
+    {
+      "context": "Footer",
+      "bindings": {
+        "j": "footer:down",
+        "k": "footer:up"
+      }
+    }
+  ]
+}