Catch the branch up with dev (45 commits) so testers can run the perf work
against current dev.
Conflict resolutions:
- downloaders/requests.py: keep the branch's racing-gated read1, adaptive
controller speed reporting and byte-range slice guards; take dev's
content-encoding checks (raw reads are skipped on an encoded body) and its
rolling SpeedWindow for the no-controller speed fallback. The single-URL
ranged-parallel gate now requires no speed limit and no caller Range.
- service.py / session.py: keep the branch's TimeoutHTTPAdapter and retry
config, raise POOL_MAX_SIZE to 64 so dev's pool-starvation fix survives
(pool_block=True stalls threads on a pool smaller than the in-flight count).
- docs: dev split configuration.md into per-area pages, so the branch's rnet
network option rows moved to reference/configuration/network.md.
imSp4rky