Fix Redis in immich_cuda: install redis-server directly instead of Docker mods

Apply the same Redis fix from the immich addon to immich_cuda:
- Remove DOCKER_MODS env var from Dockerfile and config.yaml
- Add redis-server to PACKAGES for direct installation
- s6-rc service files, redis.conf, and 20-folders.sh were already updated

This prevents ECONNRESET errors caused by Docker mods failing to install
Redis at runtime (issue #2615).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: alexbelgium <44178713+alexbelgium@users.noreply.github.com>

immich/rootfs/defaults/redis.conf

@@ -0,0 +1,64 @@
+## custom configuration file, please be aware that changing options here may break things
+## uncomment what you need to adjust, leave commented to use default settings
+## see https://redis.io/topics/config for help
+
+#protected-mode yes
+#tcp-backlog 511
+#timeout 0
+#tcp-keepalive 300
+#databases 16
+#save 900 1
+#save 300 10
+#save 60 10000
+#stop-writes-on-bgsave-error yes
+#rdbcompression yes
+#rdbchecksum yes
+#dbfilename dump.rdb
+#rdb-del-sync-files no
+#replica-serve-stale-data yes
+#replica-read-only yes
+#repl-diskless-sync no
+#repl-diskless-sync-delay 5
+#repl-diskless-load disabled
+#repl-disable-tcp-nodelay no
+#replica-priority 100
+#acllog-max-len 128
+#lazyfree-lazy-eviction no
+#lazyfree-lazy-expire no
+#lazyfree-lazy-server-del no
+#replica-lazy-flush no
+#lazyfree-lazy-user-del no
+#oom-score-adj no
+#oom-score-adj-values 0 200 800
+#appendonly no
+#appendfilename "appendonly.aof"
+#appendfsync everysec
+#no-appendfsync-on-rewrite no
+#auto-aof-rewrite-percentage 100
+#auto-aof-rewrite-min-size 64mb
+#aof-load-truncated yes
+#aof-use-rdb-preamble yes
+#lua-time-limit 5000
+#slowlog-log-slower-than 10000
+#slowlog-max-len 128
+#latency-monitor-threshold 0
+#notify-keyspace-events ""
+#hash-max-ziplist-entries 512
+#hash-max-ziplist-value 64
+#list-max-ziplist-size -2
+#list-compress-depth 0
+#set-max-intset-entries 512
+#zset-max-ziplist-entries 128
+#zset-max-ziplist-value 64
+#hll-sparse-max-bytes 3000
+#stream-node-max-bytes 4096
+#stream-node-max-entries 100
+#activerehashing yes
+#client-output-buffer-limit normal 0 0 0
+#client-output-buffer-limit replica 256mb 64mb 60
+#client-output-buffer-limit pubsub 32mb 8mb 60
+#hz 10
+#dynamic-hz yes
+#aof-rewrite-incremental-fsync yes
+#rdb-save-incremental-fsync yes
+#jemalloc-bg-thread yes