…ript never yields

An agent's preview_navigate on a tab whose page script never yields does
not land on the new page: with readiness "load" it times out, and with
readiness "none" the navigation never commits. The fake renderer models a
busy main thread that Chromium stops on Runtime.terminateExecution.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

A same-site navigation shares the renderer, so a page script that never
yields kept the old document: navigate timed out with readiness "load" and
never committed with "none". Before an agent navigate or a viewer address
bar, back/forward, reload or hard reload, probe the page with a trivial
Runtime.evaluate and send Runtime.terminateExecution only if it does not
answer within 1s. Terminating unconditionally would hit the next script on
an idle renderer, possibly the new page's first one. The probe shares
evaluate's race-and-terminate, and spends the navigate's own timeout.

Fixes #28141

Co-Authored-By: Claude Opus 5.5 <[email protected]>

…er navigation

The busy-script probe now waits at most the navigation's own timeout, so a
short timeoutMs is not delayed by the probe's 1s bound. Viewer navigate,
back, forward and reload are covered by a test on a page whose script never
yields.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

Co-Authored-By: Claude Opus 5.5 <[email protected]>

Co-Authored-By: Claude Opus 5.5 <[email protected]>

# Conflicts:
#	apps/server/src/preview/ServerBrowser.test.ts
#	apps/server/src/preview/ServerBrowserPage.ts

AI-assisted; verified with the tests and tools listed above.

goBack and goForward share one code path.

AI-assisted; verified with the tests and tools listed above.

# Conflicts:
#	apps/server/src/preview/ServerBrowser.test.ts

An unanswered probe could spend the whole budget when it was 1s or less,
leaving goto 1 ms. A cross-site navigation, which leaves a hung page by
itself, then failed where main succeeded.

AI-assisted; verified with the tests and tools listed above.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

Probing before goto took time from a cross-site navigation that would
otherwise have left the hung page in a new renderer, so it could miss a
deadline that main met. goto now starts at once with the caller's full
timeout, and the probe runs alongside it to stop a hung same-site script.

AI-assisted; verified with the tests and tools listed above.

Co-Authored-By: Claude Opus 5.5 <[email protected]>