Add register-by-signature, web fixes, bin scripts, docs

- Register by signing service key: GET /v1/service-key, POST /v1/auth/register-by-signature
- Login auto-attempts register first for new users
- Web: default API URL momswap.produktor.duckdns.org, /libs/ static handler
- Docker: webbuild stage for geo-api-client, copy web+libs to runtime
- Bin scripts: test.sh, run.sh, up.sh, down.sh
- docs/ed25519-security-use-cases.md: use cases, message formats, examples
- SERVICE_PUBLIC_KEY env (defaults to ADMIN_PUBLIC_KEY)

Made-with: Cursor

docker-compose.yml

@@ -68,3 +68,16 @@ services:
         - action: rebuild
           path: ./Dockerfile
 
+  test:
+    build:
+      context: .
+      dockerfile: Dockerfile
+      target: test
+    image: momswap-backend:test
+    volumes:
+      - .:/src
+    working_dir: /src
+    user: root
+    profiles:
+      - test
+