refactor : migrate VERSION file to config/version.yaml

Same versioning system as SIRH/Lesstime. Updates nuxt.config.ts,
Dockerfile, deploy.sh, auto-tag CI, and release script.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

deploy/docker/Dockerfile.prod

@@ -19,7 +19,6 @@ COPY migrations migrations/
 COPY public public/
 COPY src src/
 COPY templates templates/
-COPY VERSION VERSION
 
 RUN composer dump-autoload --optimize --no-dev
 
@@ -31,6 +30,7 @@ COPY frontend/package.json frontend/package-lock.json ./
 RUN npm ci
 
 COPY frontend/ ./
+COPY config/version.yaml /app/config/version.yaml
 ENV CI=1 \
     NUXT_TELEMETRY_DISABLED=1 \
     NUXT_PUBLIC_API_BASE_URL=/api \