fix: rclone PC-to-PC sync — serve backups, chat-history, uploads via filters; save source before Sync Now

The WebDAV server was narrowed to serve only backups/ (to stop exposing
.env), but the receiver still pulls /backups, /chat-history and /uploads,
so every sync failed with "directory not found". Serve the app root
filtered with --include to just those three folders; everything else
(.env, source, config/key files) returns 404.

Sync Now now saves the typed source IP/port before pulling, since the
pull reads the saved config.

stop-app.sh also frees port 8080: kill -9 on the backend orphans the
rclone child, which then keeps the port with stale settings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

stop-app.sh

@@ -1,7 +1,9 @@
 #!/bin/bash
 
 # Kill processes by port (backend 5000, selenium 5002, patient extractor 5001, payment OCR 5003, frontend 3000/3001)
-for PORT in 5000 5001 5002 5003 3000 3001; do
+# Also kill the rclone WebDAV server the backend spawns (8080) — kill -9 on the backend orphans it,
+# and a leftover one keeps the port so the next start serves with stale settings.
+for PORT in 5000 5001 5002 5003 3000 3001 8080; do
   PIDS=$(lsof -ti :$PORT 2>/dev/null)
   if [ -n "$PIDS" ]; then
     echo "Killing port $PORT (PID $PIDS)"