fix: backport #7995 — fix tslib and npm ci in ci/tests/specs (#8065)

## Summary
Full backport of #7995 to release-5.12.

- Adds `tslib` as an explicit dependency in
`ci/tests/specs/package.json` to fix `Cannot find module 'tslib'` error
in portman contract tests
- Commits `package-lock.json` and removes it from `.gitignore` for
deterministic builds
- Changes `npm install --ignore-scripts` to `npm ci` in
`ci/tests/specs/Taskfile.yml`

**Note:** The policy schema changes (`PostExpiryAction` `omitzero` tag
and associated tests) from #7995 are excluded because the
`PostExpiryAction` field does not exist in release-5.12.

## Test plan
- [ ] CI Tests job passes on this PR
- [ ] Portman contract tests no longer fail with `Cannot find module
'tslib'`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: buger

.gitignore

@@ -76,7 +76,6 @@ main
 /coprocess/*.pb.go-e
 ci/tests/specs/tmp
 ci/tests/specs/node_modules
-ci/tests/specs/package-lock.json
 ci/tests/specs/gateway.collection.postman.json
 ci/tests/specs/.env
 ci/tests/specs/apps

ci/tests/specs/Taskfile.yml

@@ -13,7 +13,7 @@ tasks:
     desc: "Run the OpenAPI specification tests"
     cmds:
       - venom run testdata/populate_gateway_test_data.yaml --var bearerToken=$PORTMAN_API_Key  --stop-on-failure && rm venom*.log
-      - npm install --ignore-scripts
+      - npm ci
       - npm start
 
   build: