Load color tag presets from an editable presets.json file

The presets move from app.js to presets.json, built into the binary and
served by /api/presets. PRESETS_FILE (default /data/presets.json) replaces
the list when present; it is read again each time Settings opens and the
built-in list is used if it is invalid. docs/presets.md (EN/FR) explains
each preset and the file format.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -18,6 +18,7 @@ services:
       AUTH_USER: ${AUTH_USER:-}   # vide = pas d'authentification, on delegue ca au reverse proxy traefik
       AUTH_PASS: ${AUTH_PASS:-}
       LOGIN_LOGO: ${LOGIN_LOGO:-}     # PNG affiche sur la page de connexion (chemin dans le conteneur, voir volumes)
+      PRESETS_FILE: ${PRESETS_FILE:-} # prereglages de tags (defaut /data/presets.json, voir docs/presets.fr.md)
       OIDC_ISSUER: ${OIDC_ISSUER:-}
       OIDC_CLIENT_ID: ${OIDC_CLIENT_ID:-}
       OIDC_CLIENT_SECRET: ${OIDC_CLIENT_SECRET:-}
@@ -41,6 +42,8 @@ services:
       - /run/log/journal:/host/run/log/journal:ro     # journal systemd volatile
       # logo de la page de connexion, avec LOGIN_LOGO=/config/logo.png dans .env
       # - ./logo.png:/config/logo.png:ro
+      # prereglages de tags personnalises, avec PRESETS_FILE=/config/presets.json dans .env
+      # - ./presets.json:/config/presets.json:ro
     labels:
       logstream.exclude: "true"      # pas de collect des logs logstream