Docs: update proxy architecture for upstream keepalive
Update flyio-proxy, forgejo, routing, manage-flyio-proxy,
expose-service-publicly, and mise-tasks docs to reflect:
- Upstream keepalive pools replacing variable-based proxy_pass
- proxy_ssl_name requirement for upstream blocks
- MagicDNS readiness check in start.sh
- fly-reload task for DNS re-resolution
- Crawler mitigation (robots.txt, archive redirect, release caching)
- Forgejo /metrics endpoint and archive cleanup cron
- cv.eblu.me in routing and exposed services tables
- upstream_response_time histogram metric
- Changelog fragment
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Erich Blume
a700befd5b