Fix DDC detection after display hot-plug

[olujicz]

Summary

• retry automatic DDC capability detection after a newly connected display initially appears unsupported
• bound retries to 250 ms and 1 second, and stop when the display disconnects, hardware control is disabled, or support is detected
• inject display topology and refresh hooks so the timing behavior can be tested without touching live display state
• add a regression test for a transient unsupported result followed by successful hardware brightness detection

Root cause

Core Graphics can report a display as active before its DDC/I²C service is ready. Dimmerly cached the first failed hot-plug probe as permanently unsupported, so subsequent display refreshes skipped it. Toggling Hardware Control forced a later probe and detected the display correctly.

Impact

Compatible USB-C/DisplayPort displays should become available for hardware control automatically after hot-plugging, without requiring the Hardware Control setting to be toggled.

Validation

• just check
• manual ANMITE USB display hot-plug test confirmed the fix
• commit hooks: SwiftFormat, SwiftLint, and Gitleaks