Several improvements

* Make Dockerfile build and run correctly on alpine, fix missing sqlite
* Make config shared to avoid reading from file on each request
* Correctly handle Signals to gracefully stop database connection and
  to speed up shutdown, relevant for docker deployment
* Correctly check for sqlite error on table creation

Dockerfile

@@ -2,10 +2,12 @@ FROM thevlang/vlang:alpine AS build
 
 WORKDIR /tmp/app
 COPY . .
-RUN v -prod .
+RUN v -prod -o highscore-server .
 
 FROM alpine:latest
 
+RUN apk --no-cache add sqlite-dev
+
 WORKDIR /app
 COPY --from=build /tmp/app/highscore-server .
 COPY --from=build /tmp/app/config.example.toml ./config.toml