Add night mode: hold-to-blackout with progressive dimming

[datboip]

Summary

Redesigned brightness and blackout UX for touchscreen boards. Replaces the old blackout button (which overlapped the dimmer zone) with a gesture-based system using progressive screen dimming as visual feedback.

Changes

• Entry: Hold top or bottom zone for 2.5s → screen progressively dims as feedback → enters brightness mode
• Brightness adjustment: Tap top half = brighter, tap bottom half = dimmer (clean 50/50 split, no zone conflicts)
• Blackout: Hold anywhere for 3s → screen darkens each second (2/3 → 1/3 → off)
• Wake: Tap while blacked out → restores to last saved brightness level
• Auto-save: Exits and saves after 4s of no touch (no manual save button needed)
• Quick blackout during scans: Hold top zone 3s → immediate blackout
• Ultra-low brightness levels (1%, 3%, 6%) for pitch dark environments — addresses Brightness options #1091

Files Changed

• MenuFunctions.cpp — brightness mode UX, entry gesture, blackout logic, wake-from-blackout restore

Removed

• Blackout button (caused zone overlap with dimmer)
• Middle-zone "save" tap (replaced by auto-save on idle)
• Fixed 1% wake brightness (now restores to saved level)

Test plan

• Hold top/bottom zone 2.5s from main menu → screen dims progressively → brightness mode opens
• Release early during hold → screen restores, no mode change
• Tap top half in brightness mode → brightness increases
• Tap bottom half → brightness decreases
• Stop touching for 4s → auto-saves and exits to menu
• Hold anywhere 3s in brightness mode → screen darkens each second → blackout
• Tap while blacked out → wakes at last saved brightness (not 1%)
• Start a scan, hold top zone 3s → quick blackout
• brightness -s 0 via CLI → sets to 1% (ultra-low)
• Brightness persists across reboot

🤖 Generated with Claude Code

[sweetwompum]

Secondary bonus of doubling the battery life.