feat: report newly opened pages in the action response

[ZayanKhan-12]

What

When a click opens a new page (link with target=_blank, window.open()), the tool response now says so and includes the list of open pages. Previously the response only said "Successfully clicked on the element", so clients could not perceive that a new tab/window had opened and assumed the click had no effect.

How

• WaitForHelper now listens for the page's popup event while the action runs and reports newPagesOpened in WaitForEventsResult (alongside the existing navigatedToUrl). This automatically covers every input tool that uses waitForEventsAfterAction (click, click_at, fill, press_key, etc.).
• McpResponse.attachWaitForResult() calls the existing setIncludePages(true) when a new page was opened, reusing the exact same page-list formatting as list_pages — no new format is introduced.
• A note line and structuredContent.newPagesOpened are emitted next to the existing Page navigated to … handling.

Token-conscious per the discussion in #367: the page list is only attached when a new page actually opened during the action; responses for ordinary clicks are unchanged, and no snapshot/tree is included.

Before

Successfully clicked on the element

After

Successfully clicked on the element
The action opened a new page. See the list of pages below and call select_page to switch to a page.
## Pages
1: My test page (about:blank) [selected]
2: about:blank

(sample captured from the new test run)

Testing

• npm run build — pass
• npm run test:no-build — full suite pass (exit 0)
• new test: input > click > reports newly opened pages proves a window.open click surfaces the note and the ## Pages list
• npm run check-format — pass
• node scripts/generate-docs.ts — no doc changes (no tool descriptions/schemas touched)

Fixes #367

🤖 Generated with Claude Code

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[Lightning00Blade]

Looked though the code, we can be explicit and return the page that was open.
Puppeteer creates a single object so from then we can update the snapshot and return only what page data was opened rather then returning the full list and leaving AI to try to figure it out.

[Lightning00Blade]

The idea makes sense, but the approach would be better if we only say what was opened.