chore(release): 0.2.2 — keep all Symfony components on 7.4

- Add symfony/flex so extra.symfony.require "7.4.*" is enforced for
  transitive components (dependency-injection had drifted to 8.0.15)
- Group Symfony packages in Renovate and restrict them to ~7.4
- Copy symfony.lock in Docker builds so Flex doesn't re-apply recipes
- Add missing 0.2.1 changelog section and cut 0.2.2

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

Dockerfile

@@ -17,7 +17,7 @@ WORKDIR /app
 # ── deps stage (prod vendor) ───────────────────────────────────────────────────
 FROM base AS deps
 COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
-COPY composer.json composer.lock* ./
+COPY composer.json composer.lock* symfony.lock ./
 RUN composer install \
     --no-dev \
     --no-scripts \