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.

.env.example

@@ -0,0 +1,10 @@
+# Server (docker-compose.yml)
+IMAGE=
+HOST_PORT=3041
+DEVICE_TOKEN=change-me
+CLIP_TTL_SECONDS=86400
+SHOT_TTL_SECONDS=1209600
+MAX_UPLOAD_BYTES=52428800
+
+# CLI scripts (source into ~/.config/scrot/env)
+SCROT_SERVER=https://scrot.example.com