Browser tools: full accessibility snapshot, trusted input, dialogs, evaluate, and tab controls (#1881)
* feat(browser): replace flat snapshot with ARIA tree and page-side refs
* feat(browser): trusted CDP input with actionability waits
* feat(browser): auto-handle javascript dialogs
* feat(browser): add browser_evaluate
* feat(browser): add scroll, resize, and close_tab tools
* fix(browser): review fixes for snapshot/input/dialog seams
* fix(browser): address review findings on dialog capture, truncation, and keypress targets
* fix(harness): drop resize check that cannot run under parked compositor surfaces
* fix(browser): second review round — snapshot fidelity, key input, dialog scoping
