fix: update Docker registry authentication for Gitea

- Use GITEA_TOKEN or github.token for authentication
- Add documentation for manual token setup if needed

NOTES.md

@@ -52,9 +52,33 @@ The old `main`/`canary` branches have the legacy stack that's harder to self-hos
      - Trigger branch: `canary` → `uwu`
      - Default source ref: `canary` → `uwu`
 
+## Gitea Setup Requirements
+
+### Container Registry Authentication
+
+The workflow tries to use `secrets.GITEA_TOKEN` or `github.token` for registry auth.
+
+**If automatic token fails**, create a Gitea Personal Access Token:
+1. Go to Gitea Settings → Applications → Generate New Token
+2. Name: `CI_REGISTRY_TOKEN`
+3. Permissions: Select `package:write`
+4. Add to repository secrets as `GITEA_TOKEN`
+
+**Alternative**: Update the workflow to use username/password:
+- Create a secret `REGISTRY_USERNAME` with your Gitea username
+- Create a secret `REGISTRY_PASSWORD` with a personal access token
+
+### Container Registry URL Format
+
+Gitea registry format is typically:
+- `git.i5.wtf/fluxerapp/fluxer-server:tag`
+
+If the registry requires a different format, check your Gitea container registry settings.
+
 ## TODO
 
-- [ ] Modify GitHub Actions workflows for Gitea compatibility
+- [x] Modify GitHub Actions workflows for Gitea compatibility
+- [ ] Fix container registry authentication
 - [ ] Apply patches from third-party guide (if needed)
 - [ ] Configure for uwu.lc domain
 - [ ] Test CI on Gitea instance