Five senders (APNs, Web Push, webhook, ntfy, email) each carried their
own single-pass replace(/<[^>]*>/g, "") — the shape CodeQL flags as
incomplete multi-character sanitization, because a removal can re-form
the pattern it removed. Whether one particular regex happens to be
idempotent is an argument about that regex; five copies of the argument
is how the next edit quietly breaks one of them.
The shared stripHtml re-applies the strip until the string stops
changing, with an iteration cap and a bracket-dropping fallback so no
tag-shaped sequence can survive any input. Plain text passes through
unchanged, same as before. Unit tests pin the nested-tag bypass shapes
and the no-surviving-tag invariant.
Resolves CodeQL alerts 38-42.
