Translation on Firefox Translations models; new logo

- Email translation moves from LibreTranslate to our own translator
  service (translator/): Mozilla's Firefox Translations models on the
  Bergamot engine, fastText language detection (176 languages). Polish,
  English, German, French, Spanish and Italian on first start (~350 MB
  instead of ~10 GB); Admin panel > Email translation installs and
  removes languages. Built and pushed as the `translator` image.
- Every message is translated paragraph by paragraph as plain text;
  names travel with their sentence and are kept only where the model
  changed them; a sentence start the model copied ("Enclosed") is tried
  again in lower case; list markers are not sent
- The Translate button shows only for installed languages
- New logo: favicon, app/maskable/iPhone icons, notification badge,
  email logo and calendar copy regenerated; BIMI logo rebuilt in SVG
  Tiny PS with its gradients; masks render in browsers
- Launch screen background is the app's dark grey

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker/docker-compose.yml

@@ -158,22 +158,18 @@ services:
       retries: 12
     restart: unless-stopped
 
-  # Email translation (app/translation.py). The first start downloads every
-  # language model (several GB) into the volume; later starts reuse them.
-  libretranslate:
-    image: libretranslate/libretranslate:v1.9.6
-    environment:
-      LT_DISABLE_WEB_UI: "true"
-      LT_UPDATE_MODELS: "false"
+  # Email translation (translator/, app/translation.py): Firefox Translations
+  # models and fastText. The first start downloads the default languages
+  # (about 350 MB) into the volume; the admin panel adds more.
+  translator:
+    build:
+      context: ..
+      dockerfile: docker/Dockerfile.translator
+    image: webmail/translator:dev
     ports:
       - "127.0.0.1:5005:5000"
     volumes:
-      - ltmodels:/home/libretranslate/.local
-    healthcheck:
-      test: ["CMD-SHELL", "python3 -c \"import urllib.request; urllib.request.urlopen('http://127.0.0.1:5000/languages', timeout=4)\""]
-      interval: 15s
-      timeout: 6s
-      retries: 240
+      - translatordata:/data
     restart: unless-stopped
 
   greenmail:
@@ -188,7 +184,7 @@ services:
       - "127.0.0.1:3993:3993"   # IMAPS
 
 volumes:
-  ltmodels:
+  translatordata:
   pgdata:
   meilidata:
   blobs: