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fix(ui-components): defer object URL revoke in panel downloads (#1031)

`URL.createObjectURL` hands the browser a handle to the blob, and the anchor
click that follows starts the download asynchronously. Revoking the URL in the
same synchronous task can therefore tear the blob down before the browser has
taken its own reference, cancelling the download.

`saveFile` already defers its revoke to the next tick for exactly this reason,
with a comment saying so. Three UI panels hand-roll the same download instead of
calling it and revoke synchronously:

- kinematics panel "Export TSV"
- masterclass panel "Export results"
- session pill ".phnxreplay" download

The user clicks export and, depending on blob size and browser, either gets the
file or silently gets nothing. Larger exports fail more often, since a bigger
blob gives the browser a wider window in which to lose the race.

PR #992 fixed `saveFile` and stated these call sites "all revoke correctly".
They do revoke, which is why they were passed over, but they revoke in the wrong
task - so the leak was fixed there while this race stayed live here.

Defer the revoke with `setTimeout` in all three, matching `saveFile`. The
kinematics and masterclass anchors are also hidden and removed after the click,
as `saveFile` does, so an unstyled anchor never lands in the layout.

Added tests asserting the URL is not revoked synchronously and is revoked after
the tick. The kinematics and masterclass "not revoked synchronously" cases fail
before this change; the session-pill suite is new.

Fixes #1030

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

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