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>

renovate.json

@@ -9,10 +9,14 @@
   },
   "packageRules": [
     {
-      "allowedVersions": "^7.0",
-      "description": "Keep Symfony on 7.x LTS until EOL",
+      "groupName": "symfony",
+      "allowedVersions": "~7.4",
+      "description": "Keep all Symfony components on 7.4 LTS and update them together (symfony/flex enforces extra.symfony.require for transitive ones)",
       "matchPackageNames": [
-        "/^symfony//"
+        "/^symfony//",
+        "!symfony/flex",
+        "!/^symfony/polyfill-/",
+        "!/-contracts$/"
       ]
     },
     {