Add exclude input to skip CSS selectors from Axe scan

[Copilot]

Embedded iframes, third-party widgets, and user-generated content often should not be scanned. This adds an exclude input (stringified JSON array of CSS selectors) that maps directly to AxeBuilder.exclude() before analyze() is called.

Changes

• action.yml (root) — New exclude input; forwarded to the find step
• .github/actions/find/action.yml — New exclude input declared
• find/src/index.ts — Parses exclude JSON with a clear error on malformed input; passes parsed array to findForUrl
• find/src/findForUrl.ts — findForUrl and runAxeScan accept exclude?: string[]; selectors applied via reduce over axeBuilder.exclude() before analyze()
• README.md — Input documented in the inputs table and getting-started example

Usage

- uses: github/accessibility-scanner@v1
  with:
    urls: |
      https://example.com
    exclude: '["iframe", "#third-party-widget", ".user-generated-content"]'

[abdulahmad307]

Actually, I don't think this is the right approach. It would make more sense if each page/url had its own exclude list. We might want to introduce a new urlConfig input that takes a list of objects with the url as a field, and any other configuration options (as opposed to the current flat list of urls). We can keep the old flat url list as an input too for those who don't need the extra configurability