fix: initialize Minestom LoginListener at run time for native image

[mworzala]

Problem

The map-isolate native image build fails during analysis:

Detected an instance of Random/SplittableRandom class in the image heap.
  scanning root java.security.SecureRandom@...: NativePRNG embedded in
    net.minestom.server.listener.preplay.LoginListener.loginStartListener(LoginListener.java:79)

Minestom's LoginListener holds a static SecureRandom. HCNativeImageFeature blanket-initializes every net.minestom.* package at build time, so that field is constructed during image generation and lands in the image heap — which GraalVM forbids for Random/SecureRandom (cached seed values). This surfaced after the recent Minestom update.

A --initialize-at-build-time=java.security.SecureRandom flag does not help — GraalVM's DisallowedImageHeapObjects check rejects such instances regardless of init policy. The instance simply must not be created at build time.

Fix

Initialize LoginListener at run time so its SecureRandom is never constructed during image generation. This follows the existing precedent in the same file (PlayerSocketConnection, NetworkBufferImpl, etc. are already runtime-init'd to override the blanket package init).

Verification

./gradlew :bin:map-isolate:nativeCompile now succeeds locally (Finished generating 'map-isolate' in 2m 46s, 125 MB executable produced).