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-push

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+# Reads the system clipboard and pushes it to scrot as a `clip` blob.
+set -euo pipefail
+
+: "${SCROT_SERVER:?set SCROT_SERVER, e.g. https://scrot.example.com}"
+: "${DEVICE_TOKEN:?set DEVICE_TOKEN}"
+
+if [ -n "${WAYLAND_DISPLAY:-}" ]; then
+  content=$(wl-paste --no-newline)
+else
+  content=$(xclip -selection clipboard -o)
+fi
+
+curl -sf -X POST "$SCROT_SERVER/api/blobs" \
+  -H "X-Device-Token: $DEVICE_TOKEN" \
+  -H "X-Blob-Kind: clip" \
+  -H "Content-Type: text/plain; charset=utf-8" \
+  --data-binary "$content" \
+  -o /dev/null
+
+echo "clip pushed"