[codex] limit FHEM upstream concurrency

[sidey79]

What changed

• Limited Caddy's FHEM upstream connections via max_conns_per_host 20 in the shared fhem_transport block.

Why

• Parallel image loads against FHEM were reproducing intermittent 401 responses from FHEM and occasional 502 dial timeouts from Caddy.
• The tests showed the issue only under higher concurrency, so throttling the upstream is the first mitigation step.

Validation

• Reproduced the issue with parallel curl requests.
• Confirmed that the branch was pushed and is ready for a Portainer-based deployment test.

Notes

• This is a mitigation, not the root-cause fix.
• Next step is to rerun the load test after deploying this branch and compare the error rate.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Apply the FHEM connection cap to image fallback

When an image is absent from /srv/fhem-www (or the new bind mount is unreadable), this newly added fallback still proxies the /fhem/images/* burst to fhem-fhem-1:8088 through its own inline transport http. Caddy documents max_conns_per_host as a transport http option that limits that transport's connections, but this transport neither imports fhem_transport nor sets the cap, so the exact fallback path for missing/custom images bypasses the 20-connection mitigation.

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