ci: add paths-ignore to skip CI on documentation-only changes

[yingjiexu2002]

Description

Adds paths-ignore to the push and pull_request triggers in .github/workflows/ci.yml so changes that no CI step scans no longer spin up the full suite:

paths-ignore:
  - '**.md'
  - '**/LICENSE'
  - '**/.gitignore'

Two small deviations from the list suggested in the issue, both deliberate:

• docs/** dropped — the repo has no top-level docs/ directory; documentation lives in pages/ and is already covered by **.md
• LICENSE/.gitignore broadened to **/LICENSE/**/.gitignore — the repo tracks these under extensions/vscode/, pages/ and plugins/ too, and none of them is scanned by any CI step

Kept triggerable, per the issue's analysis: .yml/.yaml (scanned by verify-english-only.go), .github/workflows/**, and action.yml (checked by verify-action-pins.sh).

Doc-oriented checks are unaffected: pages-ci, deploy-pages and translation-sync have their own path-based triggers and keep running for documentation changes.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that changes existing functionality)
• Refactoring (no functional changes)
• Documentation update
• CI / Build / Tooling

How Has This Been Tested?

• YAML syntax validated; make check passes
• This PR itself touches ci.yml, which is not in the ignore list, so its CI run verifies code changes still trigger the workflow
• The doc-only skip takes effect once merged; a follow-up docs-only PR can confirm it end to end

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have signed the CLA

Related Issues

closes #905

[github-actions]

✅ OpenCodeReview: Review complete: 0 finding(s) across 1 selected item(s).

[lizhengfeng101]

LGTM