release: v2.9.6-pre

[SneezeGUI]

Release batch for v2.9.6-pre — everything that merged today plus the automation to ship it.

In this build:

• fix(s3): mine first SHA in software to fix zero-shares (#28, #10, #5) #36 — S3 zero-shares fix (first SHA in software; every share software-verified; honest ~50-55 KH/s)
• fix(wifi): explicit-credential reconnect + macOS captive-portal note (#31, #29) #37 — WiFi watchdog re-issues WiFi.begin() with NVS credentials (Connection Drops #31/Can't configure wifi #29)
• feat(board): add esp32-devkit-oled target for generic ESP32 + SSD1306 (#26) #38 — esp32-devkit-oled board target + both OLED envs in CI (Feature request- oled status display support for esp32 devkit /wroom #26)
• fix(c3/s2): correct HW SHA full double-hash instead of software (#34) #39 — C3/S2 hardware SHA with boot self-test and software fallback (C3 using bitsy software at 1k H/s not compiled HW SHA #34)
• Fix silently-broken block height and fee stats (mempool.space HTTP redirect) #44 — mempool.space HTTPS redirect fix (block height / fees were silently dead)
• fix(wifi): use data-ssid for scan-list autofill so SSIDs with spaces connect #45 — config-portal SSID-with-spaces fix

Also here:

• Honest hashrate tables in the README (the old S3 280-400 KH/s figures were invalid — zero accepted shares; C3 pending real-silicon validation)
• CHANGELOG entry
• CI now uploads factory-bin test builds on every PR (no more wetransfer firmware)
• New release.yml: pushing a v* tag builds all 17 targets and publishes a GitHub Release with factory + update binaries

After this merges: tag v2.9.6-pre and the release publishes itself.