ci(CAR-1423): disable provenance/sbom attestations on auth build-push

Add deploy-dev and deploy-uat jobs to cartsnitch/auth:dev. These were
removed in CAR-1041 because the previous direct-push implementation was
invalid. Re-add them in the post-CAR-1371+1374 frontend pattern:

- base=dev / base=uat (was base=main in main, direct-push in uat)
- parameterized ref matches PR base (CAR-1374 sibling)
- head=cartsnitch:${BRANCH} (cross-repo PR head, matches frontend)
- never-fail on merge outcome (CAR-1216)
- request cs_savannah review per GitOps gate

cc @cpfarhood

.gitea/CI_TRIGGER.md

@@ -1 +0,0 @@
-# CI trigger 20260525231507 - post-DinD verification (CAR-1042)

.gitea/workflows/ci.yml

@@ -64,6 +64,8 @@ jobs:
         with:
           context: .
           push: true
+          provenance: false
+          sbom: false
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}