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>

unittests/helm/deployment/ssh-configuration.yaml

@@ -14,7 +14,7 @@ tests:
   - it: supports defining SSH log level for root based image
     template: templates/gitea/deployment.yaml
     set:
-      image.rootless: false
+      deployment.gitea.image.rootless: false
     asserts:
       - contains:
           path: spec.template.spec.containers[0].env
@@ -24,7 +24,7 @@ tests:
   - it: supports overriding SSH log level
     template: templates/gitea/deployment.yaml
     set:
-      image.rootless: false
+      deployment.gitea.image.rootless: false
       gitea.ssh.logLevel: "DEBUG"
     asserts:
       - contains:
@@ -35,8 +35,8 @@ tests:
   - it: supports overriding SSH log level (even when image.fullOverride set)
     template: templates/gitea/deployment.yaml
     set:
-      image.fullOverride: docker.gitea.com/gitea:1.19.3
-      image.rootless: false
+      deployment.gitea.image.fullOverride: docker.gitea.com/gitea:1.19.3
+      deployment.gitea.image.rootless: false
       gitea.ssh.logLevel: "DEBUG"
     asserts:
       - contains:
@@ -47,7 +47,7 @@ tests:
   - it: skips SSH_LOG_LEVEL for rootless image
     template: templates/gitea/deployment.yaml
     set:
-      image.rootless: true
+      deployment.gitea.image.rootless: true
       gitea.ssh.logLevel: "DEBUG" # explicitly defining a non-standard level here
     asserts:
       - notContains:
@@ -58,8 +58,8 @@ tests:
   - it: skips SSH_LOG_LEVEL for rootless image (even when image.fullOverride set)
     template: templates/gitea/deployment.yaml
     set:
-      image.fullOverride: docker.gitea.com/gitea:1.19.3
-      image.rootless: true
+      deployment.gitea.image.fullOverride: docker.gitea.com/gitea:1.19.3
+      deployment.gitea.image.rootless: true
       gitea.ssh.logLevel: "DEBUG" # explicitly defining a non-standard level here
     asserts:
       - notContains: