feat(deploy): instances keep their dictionaries current, weekly, by themselves

EDRDG's licence asks of a server showing its dictionaries that it update
them at least monthly. The instance now does it alone: a `dictionaries`
service in compose, built from the curator (halkyon_learn_curator/
Dockerfile, its own unprivileged user 10001, 1 GB at most), runs `curate
update --every 7`, downloading EDRDG's files of the day once its files are
a week old and replacing them in a volume the server mounts read-only.
The curator never enters the server's image or process (decided
2026-10-09: a container of its own, weekly). The server rereads the
folder daily at 04:07 (DictionaryReloadFutureCall), loading what changed,
and loads now run one at a time. redeploy.sh builds both images.

An operator who'd rather supply the files removes the service and mounts
deploy/dictionaries/ into the server, as compose.yaml says.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

deploy/compose.yaml

@@ -1,4 +1,5 @@
-# The Halkyon Learn instance: Caddy in front, the Serverpod server, PostgreSQL.
+# The Halkyon Learn instance: Caddy in front, the Serverpod server, PostgreSQL, and
+# the dictionaries kept current beside them.
 #
 #   cd deploy
 #   cp .env.example .env && chmod 600 .env   # then fill in the secrets
@@ -57,15 +58,36 @@ services:
       FILE_LIMIT_ANONYMOUS_MB: ${FILE_LIMIT_ANONYMOUS_MB:-}
       FILE_LIMIT_IDENTIFIED_MB: ${FILE_LIMIT_IDENTIFIED_MB:-}
       FILE_LIMIT_INSTANCE_MB: ${FILE_LIMIT_INSTANCE_MB:-}
-    # The dictionary files it loads at start, those that changed since (see the
-    # server's README); read only, and empty unless the operator adds some.
+    # The dictionary files it loads at start and rereads daily, those that changed
+    # (see the server's README): those the dictionaries service keeps current, read
+    # only. To supply files yourself instead, remove that service and mount
+    # ./dictionaries here (`- ./dictionaries:/app/dictionaries:ro`).
     volumes:
-      - ./dictionaries:/app/dictionaries:ro
+      - dictionaries:/app/dictionaries:ro
     depends_on:
       postgres:
         condition: service_healthy
     logging: *logging
 
+  # Keeps the dictionary files current from EDRDG's files of the day, once they are a
+  # week old (EDRDG's licence asks it of servers showing its dictionaries at least
+  # monthly; the curator's README): in a container of its own, the curator never in
+  # the server's image or process. It only downloads (some 25 MB a week) and writes
+  # into the volume; the files are never backed up, as they can be had again.
+  dictionaries:
+    build:
+      context: ..
+      dockerfile: halkyon_learn_curator/Dockerfile
+    image: halkyon-learn-dictionaries
+    restart: unless-stopped
+    # Docker's stop signal reaches the curator through a small init.
+    init: true
+    # A conversion takes some 400 MB for a minute a week.
+    mem_limit: 1g
+    volumes:
+      - dictionaries:/dictionaries
+    logging: *logging
+
   postgres:
     image: postgres:16
     restart: unless-stopped
@@ -88,4 +110,5 @@ services:
 volumes:
   caddy_data:
   caddy_config:
+  dictionaries:
   postgres_data: