Add a browser_navigate tool for stateful, multi-page browser navigation

Problem/Motivation

browser_preview opens each page in a throwaway browser — it cannot walk a multi-page flow (open a Drupal Canvas page, go back, go forward, reload) and it re-establishes login on every single call. An AI agent verifying a build across several pages loses its session and its navigation history between calls, so it cannot reliably check things like "does Back/Forward keep the authenticated session and the right page in history".

Proposed resolution

Add a browser_navigate AI Agent tool plus a stateful navigation runner that persists the browser session (cookies via Playwright storageState) and a navigation history stack in a per-user state file between calls.

One action per call:

• {"type":"goto","url":"/page/12"}
• {"type":"back"}
• {"type":"forward"}
• {"type":"reload"}
• or an interaction: click / type / scroll / wait / resize

Login is established once and reused across calls. The chat conversation itself is untouched because navigation runs in a separate headless browser, not the user's own browser tab. The tool returns the screenshot file id, page title, visible text, console errors, and the history position (canGoBack / canGoForward).

Same use ai playwright permission gate and same-host URL guard as browser_preview.

Implementation:

• scripts/browser-navigate.mjs: restores storageState + history from a state file, performs one goto/back/forward/reload or interaction, saves state back, returns url/title/text/console/screenshot/history/index/canGoBack/canGoForward.
• PlaywrightRunner::navigate(): resolves goto URLs (same host guard as capture()), runs the script per acting user, saves the screenshot as a managed file, returns the structured result.
• BrowserNavigate #[FunctionCall] tool: one action JSON argument; same permission gate as browser_preview.

Verified locally: goto -> goto -> back -> forward -> reload keeps an authenticated session and correct history across separate process calls; each step saves a screenshot file. phpcs (Drupal + DrupalPractice) is clean.

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ❌ Reviewed by a human
• ❌ Code review by maintainers
• ❌ Full testing and approval
• ❌ Credit contributors
• ❌ Review with the product owner
• ❌ Update Release Notes
• ❌ Release

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• N/A