Merge origin/main: the operator's upload ceiling beside the disk-thread work

One conflict, in §15.3's open list, and it was two changes agreeing rather than
disagreeing: this side removed the rows for the third-party search bound and the
node-announcement bound because both are now built (AV27, AV28), while the other
side kept them and added a new one. Resolved by keeping what is genuinely still
open — per-device revocation having no CLI — and leaving the two closed.

`webrtc_server.py` merged without conflict but the two sides met inside one
function: `_upload_chunk` gained the operator's `max_upload_gb` ceiling from
there and the per-group lock and `off_disk` calls from here. Read back rather
than trusted: the operator's ceiling now sits inside the critical section that
keeps chunk ordering, and the unlink beside it goes to the disk thread with
everything else.

2893 passed. The twelve `test_sticky_header.py[firefox]` setup errors are the
open Firefox on this machine, as before.

0 files changed, 0 insertions, 0 deletions