fix(#622): one-click upgrade rides out a 502/503/504 from the proxy #937

Job	Run time
Dashboard tests (pytest + coverage)	43s
Dockerfile lint (hadolint)	4s
Frontend logic tests (node --test)	8s
Secret scan (gitleaks)	9s
Workflow audit (zizmor)	8s
Python lint + format (ruff)	10s
Dashboard image (Docker test stage)	42s
Lint per-surface (biome, yaml, markdown, proto, toml)	31s
Compose config + security hardening	7s
Build image (monero)	1m 33s
Shell tests (shellcheck + pithead suite)	4m 3s
Build image (tor)	24s
Build image (p2pool)	46s
Build image (xmrig-proxy)	31s
Build image (dashboard)	29s
	10m 28s

Provide feedback