ci: reuse the published image when its sources are unchanged

The release workflow hashes everything that goes into the image build and skips
CI and the build when the registry already has an image for that hash, so a docs
or tooling change, or a version tag, only re-points the tags. ci.yml no longer
runs on main by push: release.yml calls it when a build is needed, and running
both repeated the same suite on the same commit.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -1,10 +1,14 @@
 name: CI
 
+# Documentação e configuração de ferramenta não mudam nada que a suíte teste.
+# Na main não roda por push: o release.yml é quem a chama, e só quando a imagem
+# precisa ser reconstruída; rodar nos dois repetiria a mesma suíte no mesmo commit.
 on:
   pull_request:
+    paths-ignore: ['**.md', 'LICENSE', '.claude/**', '.superset/**']
   push:
-    branches: [main]
-  # O release.yml roda esta mesma suíte antes de publicar a imagem.
+    branches-ignore: [main]
+    paths-ignore: ['**.md', 'LICENSE', '.claude/**', '.superset/**']
   workflow_call:
 
 permissions: