Fetch games into a volume at runtime instead of baking them into the image

927MB of the image was just t7g's two CD ISOs, which can't be meaningfully
compressed (already-compressed FMV/audio). Move the smbget/unzip step out
of the Dockerfile and into scripts/fetch_games.sh, run from server.sh on
container start: it populates GAMES_HOME on first run and skips the fetch
if games are already present. run.sh mounts a named volume so the games
survive --rm restarts instead of being re-downloaded every time. Image
drops from 1.6GB to ~690MB; first container start now needs network access
to the vlda-01 SMB share to seed the volume.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NiNnj78HGx1KWyCCo39HSz

run.sh

@@ -1,4 +1,4 @@
 #/bin/bash
 
-docker run --name dosbox-novnc -d --rm --net bridge -e SCREEN_W=1536 -e SCREEN_H=960 --device /dev/snd jayfield/dosbox-novnc
+docker run --name dosbox-novnc -d --rm --net bridge -e SCREEN_W=1536 -e SCREEN_H=960 --device /dev/snd -v dosbox-games:/opt/games jayfield/dosbox-novnc