chore: expose status port in Docker/compose and document http_addr

EXPOSE 8080 in the image, publish 8080 in compose, document http_addr in the
example config, and add the CPU/memory limits so a long encode can't starve
the host.

.dockerignore

@@ -1,5 +1,6 @@
 videnc-vibe
 *.mkv
+*.mp4
 *.wav
 *.opus
 *.log
@@ -10,5 +11,6 @@ logs.db
 /originals
 /failed
 /work
+/data
 .git
 MANUAL.html