fix(ci): increase poll_timeout for H100 scale-to-zero, fix build-ci-builder rules

- poll_timeout 180s→600s: H100 provisioning takes ~3-5min from scale-to-zero
- build-ci-builder: only auto-run on push with Dockerfile changes (API
  pipelines evaluate changes=true, causing unnecessary kaniko builds)
- check: add needs:[] to decouple from prepare stage

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitlab-ci.yml

@@ -39,7 +39,8 @@ build-ci-builder:
     - kapsule
     - docker
   rules:
-    - changes:
+    - if: $CI_PIPELINE_SOURCE == "push"
+      changes:
         - infra/docker/Dockerfile.ci-builder
       when: on_success
     - when: manual
@@ -67,6 +68,7 @@ build-ci-builder:
 check:
   extends: .rust-base
   stage: check
+  needs: []
   script:
     - sccache --zero-stats || true
     - cargo check --workspace

infra/k8s/gitlab/runner-values.yaml

@@ -25,6 +25,8 @@ runners:
         namespace = "foxhunt"
         image = "rust:1.89-slim"
         privileged = false
+        # H100 scale-to-zero needs ~3-5 min to provision; default 180s times out
+        poll_timeout = 600
         # Resource limits for build pods (H100 node: 24 vCPU, 240GB)
         cpu_request = "4000m"
         cpu_limit = "16000m"