Add ScummVM support and generalize manifest zip lookup

Add scummvm to the Dockerfile. Its binary lives at /usr/games/scummvm
(Debian's convention for game packages), not reliably on $PATH under a
non-login shell, so manifests reference it by absolute path.

Generalize the manifest schema from a bare "zip" filename (implicitly
under Games\dosbox\ on the SMB share) to "zip_path" (a full path
relative to the share root), since the SCUMM games' zips live in their
own folders (Games\Monkey Island\, Games\Indiana Jones\, etc.) rather
than being colocated with their manifest like stuntcar/t7g were.
Manifests themselves still all live in the Games\dosbox\ catalog
directory regardless of where the actual zip sits.

Added and verified (install/start/stop/uninstall via monkey2) manifests
for: monkey, monkey2, atlantis, indy3, tentacle. Skipped the German CD
release of Day of the Tentacle (loose files at the zip root, no single
top-level folder - incompatible with the current extraction convention)
and Curse of Monkey Island (untested, much larger).

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

Dockerfile

@@ -11,7 +11,7 @@ ENV PATH=${PATH}:${SCRIPTS_HOME}
 # image, setup_server.py serves an HTML install UI (backed by smbget+unzip) that the user
 # drives on ${SETUP_PORT} instead of anything being auto-downloaded at container start.
 RUN apt-get update && \
-    apt-get -y install --no-install-recommends dosbox alsa-utils unzip smbclient python3 && \
+    apt-get -y install --no-install-recommends dosbox scummvm alsa-utils unzip smbclient python3 && \
     rm -rf /var/lib/apt/lists/*
 
 RUN openssl req -x509 -nodes -newkey rsa:2048 -keyout /tmp/novnc.key -out /tmp/novnc.pem -days 3650 -subj "/C=US/ST=NY/L=NY/O=NY/OU=NY/CN=NY emailAddress=email@example.com"