feat(deployment)!: move image to deployment.gitea.image

The `image` values only ever configured the Gitea container itself — registry, repository, tag, digest,
pull policy and the rootless variant are all consumed by the `gitea` container and its init containers.
Keeping them at the top level suggested a chart-wide scope that never existed and separated them from the
other container-scoped settings that already live under `deployment.gitea` (`env`, `resources`).
Moving the block makes the container configuration self-contained and continues the consolidation of all
pod- and Deployment-scoped values under the `deployment` dict.

`imagePullSecrets` intentionally stays top-level, because it is a pod-level setting that also applies to
`extraContainers` and is paired with `global.imagePullSecrets`.

BREAKING CHANGE: `image` no longer exists. Use `deployment.gitea.image` instead. Values still set under
`image` are silently ignored, which would drop a pinned `tag` or `digest` and roll out the chart default
(`appVersion`) instead — review your values before upgrading.

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

templates/gitea/secret_init.yaml

@@ -26,7 +26,7 @@ stringData:
     # END: initPreScript
     {{- end }}
 
-    {{- if not .Values.image.rootless }}
+    {{- if not .Values.deployment.gitea.image.rootless }}
     chown -v 1000:1000 /data
     {{- end }}
     mkdir -pv /data/git/.ssh
@@ -35,7 +35,7 @@ stringData:
 
     # prepare temp directory structure
     mkdir -pv "${GITEA_TEMP}"
-    {{- if not .Values.image.rootless }}
+    {{- if not .Values.deployment.gitea.image.rootless }}
     chown -v 1000:1000 "${GITEA_TEMP}"
     {{- end }}
     chmod -v ug+rwx "${GITEA_TEMP}"