feat(deployment)!: move affinity to deployment.affinity

Moving `affinity` into the `deployment` dict groups it with the other Deployment-specific values and prepares a
consistent structure for further migrations of pod-level settings.

A deprecation check is added so that existing installations fail fast with an actionable error message instead of
silently dropping the affinity rules, which would otherwise lead to pods being scheduled on unintended nodes.

BREAKING CHANGE: `affinity` no longer exists. Use `deployment.affinity` instead. Installations that still set
`affinity` will fail unless `checkDeprecation` is set to `false`.

Co-authored-by: Copilot <copilot@github.com>

templates/gitea/deployment.yaml

@@ -426,7 +426,7 @@ spec:
       nodeSelector:
         {{- toYaml . | nindent 8 }}
       {{- end }}
-    {{- with .Values.affinity }}
+    {{- with .Values.deployment.affinity }}
       affinity:
         {{- toYaml . | nindent 8 }}
     {{- end }}