Restructure scripts into dev/ and prod/ for the devcontainer

- scripts/prod: entrypoint, db-setup and schema.sql shipped in the image
- scripts/dev: seed/clear db, psql and cleanup, run natively in the
  devcontainer instead of via docker-compose
- move setup.cfg to the repo root so linters pick it up
- Makefile targets run directly in the devcontainer

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

scripts/dev/seed-db.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+set -e
+cd "$(dirname "$0")"
+
+source ../prod/db-setup.sh
+
+flask add-domain finn.st
+flask add-domain stutzenste.in
+flask reset-admin admin@finn.st admin