refactor(templates): move the templates out of the gitea subdirectory

The `templates/gitea` subdirectory did not group anything meaningful, since every template of this chart belongs to
Gitea. It only duplicated the chart name in every path and forced the unit tests to spell out
`templates/gitea/<name>.yaml`, while `_helpers.tpl` and `NOTES.txt` already lived directly in `templates`.

All templates now live in `templates`, which matches the layout of the bundled sub-charts and the Helm defaults.

The checksum helper in `templates/_secrets.tpl` built its include path from `$root.Template.BasePath` and therefore
carried the subdirectory in a `printf` format string instead of a literal path. Without adjusting it the chart failed to
render with "no template gitea/templates/gitea/secret_config.yaml associated with template gotpl".

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

unittests/helm/deployment/ssh-configuration.yaml

@@ -3,16 +3,16 @@ release:
   name: gitea-unittests
   namespace: testing
 templates:
-  - templates/gitea/deployment.yaml
-  - templates/gitea/secret_admin.yaml
-  - templates/gitea/secret_config.yaml
-  - templates/gitea/secret_gpg.yaml
-  - templates/gitea/secret_init.yaml
-  - templates/gitea/secret_inlineConfig.yaml
-  - templates/gitea/secret_metrics.yaml
+  - templates/deployment.yaml
+  - templates/secret_admin.yaml
+  - templates/secret_config.yaml
+  - templates/secret_gpg.yaml
+  - templates/secret_init.yaml
+  - templates/secret_inlineConfig.yaml
+  - templates/secret_metrics.yaml
 tests:
   - it: supports defining SSH log level for root based image
-    template: templates/gitea/deployment.yaml
+    template: templates/deployment.yaml
     set:
       deployment.gitea.image.rootless: false
     asserts:
@@ -22,7 +22,7 @@ tests:
             name: SSH_LOG_LEVEL
             value: "INFO"
   - it: supports overriding SSH log level
-    template: templates/gitea/deployment.yaml
+    template: templates/deployment.yaml
     set:
       deployment.gitea.image.rootless: false
       gitea.ssh.logLevel: "DEBUG"
@@ -33,7 +33,7 @@ tests:
             name: SSH_LOG_LEVEL
             value: "DEBUG"
   - it: supports overriding SSH log level (even when image.fullOverride set)
-    template: templates/gitea/deployment.yaml
+    template: templates/deployment.yaml
     set:
       deployment.gitea.image.fullOverride: docker.gitea.com/gitea:1.19.3
       deployment.gitea.image.rootless: false
@@ -45,7 +45,7 @@ tests:
             name: SSH_LOG_LEVEL
             value: "DEBUG"
   - it: skips SSH_LOG_LEVEL for rootless image
-    template: templates/gitea/deployment.yaml
+    template: templates/deployment.yaml
     set:
       deployment.gitea.image.rootless: true
       gitea.ssh.logLevel: "DEBUG" # explicitly defining a non-standard level here
@@ -56,7 +56,7 @@ tests:
           content:
             name: SSH_LOG_LEVEL
   - it: skips SSH_LOG_LEVEL for rootless image (even when image.fullOverride set)
-    template: templates/gitea/deployment.yaml
+    template: templates/deployment.yaml
     set:
       deployment.gitea.image.fullOverride: docker.gitea.com/gitea:1.19.3
       deployment.gitea.image.rootless: true