HYPERFLEET-1024 - chore: switch spectral lint to CLI with github-actions format

Replace stoplightio/spectral-action (Docker, hides output behind GitHub API
annotations) with a direct npx spectral lint invocation using --format
github-actions. This format emits ::error and ::warning workflow commands
to stdout, which GitHub Actions renders as inline PR annotations natively
without requiring checks:write or any API call. Output is fully visible in
step logs. Remove checks:write permission as it is no longer needed.

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

Author: mliptak0

.github/workflows/ci.yml

@@ -11,7 +11,6 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: read
-      checks: write
 
     steps:
       - name: Checkout code
@@ -44,9 +43,8 @@ jobs:
           fi
 
       - name: Lint OpenAPI schemas
-        uses: stoplightio/spectral-action@v0.8.13
-        with:
-          file_glob: schemas/**/openapi.yaml
+        run: |
+          npx spectral lint schemas/core/openapi.yaml schemas/gcp/openapi.yaml --format github-actions
 
       - name: Check version bump
         env: