The source tag credits an outlet Pete is relaying (`ars technica`). On
his own reporting it rendered as a trailing `pete` under a message he
already sent - him signing his own name. Drop Source on adventure posts
and omit the tag line entirely when there's nothing to credit; RSS posts
keep theirs.
- Route image-validation, Matrix image-download, and wayback/archive.today
fetches through safehttp so feed-controlled URLs can't reach loopback/
RFC1918/cloud-metadata IPs (incl. via redirects).
- Cap feed body size with safehttp.LimitedBody (16 MiB) to prevent OOM.
- Fail closed if matrix.pickle_key is unset/<16 chars; drop the hardcoded
"pete_pickle_key" default that silently weakened E2EE-at-rest.
- Gate !post behind a matrix.admins allowlist; empty = disabled (channel
rooms are public, so empty must not mean anyone).
- Reject /\host open-redirect bypass in post-login safeNext.
- Allowlist http(s) schemes for the Matrix link href; escape JSON embedded
in inline <script> (prefs/sources blobs).
