{% comment %}
The polled half of a thread: pause banner, compliance notice, message history.
EVERY string below arrived from a stranger (SECURITY-BASELINE §2) — message
text, captions, card titles, button labels, attachment URLs. Three rules hold
here and they are checked by apps/inbox/tests/test_hostile_content.py:
* Nothing is marked safe. Default autoescaping is the whole defence for text.
* No URL reaches an href or a src unless apps/inbox/rendering.py already put
it in an Image/Link/Card, which it only does after
apps.common.validators.is_renderable_url said http(s). A rejected one is
already a Tombstone by the time it gets here, so there is no {% if %} in
this file deciding it — the decision is made in Python, once. A Media part
is the exception that proves it: its URL was *reversed* by rendering.py
rather than received from anyone, and running a stranger-string check over
one of our own routes would be theatre.
* `rel="noopener noreferrer"` and `target="_blank"` on every outbound link:
the destination is chosen by the same stranger.
An but never an