fix(docker): robust jar glob, lavalink healthcheck + startup order, restrict 2333 to loopback

- COPY build/libs/*.jar instead of hardcoded discord-bot-1.0.0.jar (breaks on version bump)
- lavalink: add /v4/info healthcheck; bot waits for service_healthy before start;
  lavalink now depends on spotify-tokener
- lavalink host port bound to 127.0.0.1 (bot talks over docker network; no internet exposure)
- .dockerignore: exclude .github + lavalink/ from build context

Dockerfile

@@ -8,7 +8,7 @@ RUN ./gradlew jar --stacktrace
 FROM eclipse-temurin:26-jre-alpine
 RUN addgroup -S bot && adduser -S bot -G bot
 WORKDIR /app
-COPY --from=builder /build/build/libs/discord-bot-1.0.0.jar app.jar
+COPY --from=builder /build/build/libs/*.jar app.jar
 COPY data/prompts /app/prompts
 COPY data/knowledge /app/knowledge
 RUN mkdir -p /app/data /app/logs && chown -R bot:bot /app