fix(ci): add provenance: false to fix registry push failures

OCI attestation manifests fail to push on Gitea registry when image
layers already exist (cross-repo blob references). Disabling provenance
generation on all four build-push-action steps ensures a simple single
manifest push that Gitea handles reliably.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.gitea/workflows/ci.yml

@@ -91,6 +91,7 @@ jobs:
       - name: Build and push API image
         uses: docker/build-push-action@v6
         with:
+          provenance: false
           context: .
           file: Dockerfile
           target: runner
@@ -104,6 +105,7 @@ jobs:
       - name: Build and push Migrate image
         uses: docker/build-push-action@v6
         with:
+          provenance: false
           context: .
           file: Dockerfile
           target: migrate
@@ -117,6 +119,7 @@ jobs:
       - name: Build and push Seed image
         uses: docker/build-push-action@v6
         with:
+          provenance: false
           context: .
           file: Dockerfile
           target: seed
@@ -130,6 +133,7 @@ jobs:
       - name: Build and push Reset image
         uses: docker/build-push-action@v6
         with:
+          provenance: false
           context: .
           file: Dockerfile
           target: reset