ci(helm): harden manual dispatch + skip PR checks for helm-only changes

- override appVersion via yq + env (no sed escape issues for user input)
- fall back REF_SLUG to 'manual' when sanitization strips it empty
- ignore helm prerelease workflow files in pr_checks.yml so unrelated
  CI edits don't trigger the full typecheck/unit/e2e suite

Author: nicktrn

.github/workflows/helm-prerelease.yml

@@ -113,6 +113,9 @@ jobs:
           else
             SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
             REF_SLUG=$(echo "${{ github.ref_name }}" | tr '/' '-' | tr -cd 'a-zA-Z0-9-')
+            if [[ -z "$REF_SLUG" ]]; then
+              REF_SLUG="manual"
+            fi
             PRERELEASE_VERSION="${BASE_VERSION}-${REF_SLUG}.${SHORT_SHA}"
           fi
           echo "version=$PRERELEASE_VERSION" >> $GITHUB_OUTPUT
@@ -124,8 +127,10 @@ jobs:
 
       - name: Override appVersion
         if: github.event_name == 'workflow_dispatch' && inputs.app_version != ''
+        env:
+          APP_VERSION: ${{ inputs.app_version }}
         run: |
-          sed -i "s/^appVersion:.*/appVersion: ${{ inputs.app_version }}/" ./hosting/k8s/helm/Chart.yaml
+          yq -i '.appVersion = strenv(APP_VERSION)' ./hosting/k8s/helm/Chart.yaml
 
       - name: Package Helm Chart
         run: |

.github/workflows/pr_checks.yml

@@ -7,6 +7,8 @@ on:
       - "docs/**"
       - ".changeset/**"
       - "hosting/**"
+      - ".github/workflows/helm-prerelease.yml"
+      - ".github/workflows/helm-pr-prerelease.yml"
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}