Refine SSD1677 four-mode refresh waveforms

[ainyan03]

Summary

• keep SSD1677 Fast and Fastest updates differential and preserve untouched black, gray, and white pixels with state-aware hold groups
• use an 8-frame Fastest waveform and a stronger 12-frame Fast waveform
• make Text refresh aware of the Mode 2 ping-pong plane parity
• replace the separate Quality precondition activation with one fixed LUT that performs four rapid black/white round trips before forming the target four-gray image
• keep Quality and Text as single user-visible refresh calls

Hardware validation

Tested on an M5PaperMono SSD1677 panel using M5Unified 0.2.18.

• Fastest completed 60 consecutive dirty updates at 88 ms average while four untouched gray references remained distinct
• a Quality or Text UI followed by 30 Fastest selection moves kept the header, four-gray sidebar, frame, and footer stable outside the dirty rectangle
• the accepted Fastest lightening adjustment retained the same 105 ms average in the navigation test and reduced erased black cursor residue to a visually negligible level
• Text produced the correct black, dark gray, light gray, and white order after reset and after both odd and even Mode 2 entry states
• Quality completed in about 1495 ms with four rapid black/white round trips inside one Mode 1 activation

Checks

• PlatformIO SSD1677/M5Unified test firmware build
• SSD1677 grayscale transition logic test with -Wall -Wextra -Werror
• git diff --check