CHANGED IN THIS VERSION: the time anchor is now ON by default, and — see
"Fixed" below — it can actually run for the first time in this package. In
earlier builds the file implementing it was missing from the package, so the
feature silently did nothing. PRIVACY.md has been updated: it previously said
the extension makes no network requests at all, which was true only while the
feature was off by default.

Feature : "Time anchor" — no longer a setting, it is always on
Endpoints: three, tried in order until one answers — the network is
decentralised and a single host would defeat the purpose:
https://api.drand.sh/<chain>/public/latest
https://drand.cloudflare.com/<chain>/public/latest
https://api2.drand.sh/<chain>/public/latest
<chain> is the fixed quicknet hash
52db9ba70e0cc0f6eaf7803dd07447a1f5477735fd3f661792ba94600c84e971
(hard-coded in zeitanker.js, not user-supplied). Each attempt has
an AbortController timeout.
Purpose : Fetches a public random value from the drand network (League of
Entropy) and writes it into the capture. Since nobody could know
that value in advance, it shows the capture is not older than that
round — without relying on the device clock, which the user can
set freely.
Sent : nothing. Plain GET, no headers identifying the user, no page data,
no URL of the captured page. The response is a random value, a
round number and a timestamp, identical for everyone asking in
that round.
Failure : the capture is saved without an anchor. No error, no retry loop.

No other network path exists. Two further fetch() calls appear in the source
and are local by construction: result.js reads back a blob: URL it created
itself, and background.js converts a data: URL from captureVisibleTab into a
blob. Neither leaves the machine.