migrate: change repoURLs from GitHub to Gitea

Update all ArgoCD Application references to use Gitea (github0213.com)
instead of GitHub for K3S-HOME/applications repository.
Also update docusaurus to use gitea-creds for Image Updater write-back.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

code-server/argocd.yaml

@@ -14,10 +14,10 @@ spec:
     helm:
       valueFiles:
       - $values/code-server/helm-values.yaml
-  - repoURL: https://github.com/K3S-HOME/applications.git
+  - repoURL: https://github0213.com/K3S-HOME/applications.git
     targetRevision: main
     ref: values
-  - repoURL: https://github.com/K3S-HOME/applications.git
+  - repoURL: https://github0213.com/K3S-HOME/applications.git
     targetRevision: main
     path: code-server
   destination: