v0.32.0 — a tab's owner is not recorded only where the page can erase it

A tab's owner is no longer recorded only in a place the page can erase

The title tag ([1-2] my-agent …) is how wb close --agent and the raw-CDP lane find an agent's
own tabs. But the title belongs to the page. An SPA rewrites it whenever it likes — X does, for
the unread count — and a MutationObserver puts the tag back. Anything that replaces the document
takes that observer with it, and from then on the tab cannot be identified at all.

Reported 2026-10-03: a tab read [1-?] influencer-whitegun (1) WhiteGun on X… right after opening
and plain (1) WhiteGun on X… minutes later. wb close --agent influencer-whitegun then answered
"no open tabs", and five tabs were left open because none could be told apart from a person's.
The raw-CDP lane refused to attach for the same reason, advising restarts that could not help.

The stamp has always also set window.__wbrowserAgent, which survives title rewrites. That is now
used as a second route:

• wb close --agent <name> scans titles first (one HTTP call for every tab at once); if that
  finds nothing it asks each page directly, and says so — "title tags were gone (the page rewrote
  them); identified 1 tab(s) by asking the page instead".
• The raw-CDP lane does the same before refusing to attach.
• Only exact answers are claimed. A page that does not answer is left alone — closing a tab we
  could not identify is the accident this exists to prevent, so silence is never consent.

Measured end to end: with the title tag stripped and the observer disconnected (the reported state),
wb read reached the tab and wb close --agent closed exactly it, leaving an untagged tab on the
same URL untouched.

🔵 A 3-minute watch found no natural decay — tag and observer were alive at every 20s sample. The
loss is event-driven, not time-driven, so this fix deliberately does not depend on identifying the
event: whenever the title tag is missing, ask the page.