Initial scaffold: blob store server, CLI scripts, and PWA share target

Clipboard/screenshot sync across own devices via a single DEVICE_TOKEN-gated
blob store, plus a small installable web app so a phone can push/pull
clips and share screenshots via the OS share sheet.

cli/scrot-clip-pull

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Fetches the latest `clip` blob from scrot and writes it into the local
+# system clipboard.
+set -euo pipefail
+
+: "${SCROT_SERVER:?set SCROT_SERVER, e.g. https://scrot.example.com}"
+: "${DEVICE_TOKEN:?set DEVICE_TOKEN}"
+
+response=$(curl -sf -w '\n%{http_code}' "$SCROT_SERVER/api/clip/latest" \
+  -H "X-Device-Token: $DEVICE_TOKEN")
+
+status="${response##*$'\n'}"
+body="${response%$'\n'*}"
+
+if [ "$status" = "204" ]; then
+  echo "no clip yet" >&2
+  exit 1
+fi
+
+if [ -n "${WAYLAND_DISPLAY:-}" ]; then
+  printf '%s' "$body" | wl-copy
+else
+  printf '%s' "$body" | xclip -selection clipboard
+fi
+
+echo "clip pulled into clipboard"