Fix and extend Endgame Gear 8K wired mice configuration support

[qsxcv]

Summary

OpenMouse already recognized four wired Endgame Gear 8K models and exposed their
core CPI, polling, sensor, switch, and button settings. That implementation used
mostly shared OP1 8K assumptions, however, and had problems with feature-report
alignment, firmware parsing, active CPI stages, model-specific limits, and button
record offsets.

This change corrects and extends that existing support. It adds XM2 8K v2 support
and defines an explicit capability profile for each supported model:

• OP1 8K
• XM2 8K
• OP1 8K Purple Frost
• OP1 8K v2
• XM2 8K v2

Existing controls continue to use read-modify-write config updates. Writes now
also wait for the device ACK and verify the stored config before reporting success.

Development notes:

• qsxcv/UnofficialEGGWebConfig was used as the implementation reference.
• These commits were generated with AI (GPT-5.6 Sol, xhigh reasoning) and have not been fully reviewed by a human.

Changes

• Add XM2 8K v2 to the existing OP1 8K, XM2 8K, Purple Frost, and OP1 8K v2 device list.
• Replace shared OP1 8K assumptions with per-model CPI, LOD, sensor, and firmware capabilities.
• Fix config response alignment for data returned through either the A0 or A1 feature report.
• Retry config transfers, require write acknowledgements, and verify stored values after writes.
• Fix firmware response handling and decode BCD versions such as V1.07 and V1.37.
• Read, select, and update the active CPI stage instead of assuming or overwriting other stages.
• Clamp custom DPI, CPI-stage, and fixed-CPI inputs to values supported by the active model.
• Retain the existing 1,000 Hz through 8,000 Hz choices and add 125 Hz, 250 Hz, and 500 Hz divider options.
• Keep the existing Motion Sync, angle snapping, ripple control, slamclick, and motion-jitter controls while applying the correct model-specific restrictions.
• Keep the existing GX and multiclick controls while correcting their physical button record offsets.
• Correct the shifted button mapping layout and preserve the hidden firmware mapping record.
• Extend button support with wheel actions, left-handed mode, keyboard shortcuts, fixed CPI, media actions, and system actions.
• Add Glass Mode for Purple Frost and both v2 models.
• Add sensor angle tuning, maximum sensor FPS, and lift-off LED control for v2 models.
• Add reload and factory reset actions.
• Add protocol tests for the corrected model profiles, firmware format, config framing, CPI rules, and button layout.

Model-specific behavior

• OP1 8K and XM2 8K use PAW3395 and cannot enable Motion Sync at 8,000 Hz.
• Purple Frost, OP1 8K v2, and XM2 8K v2 use PAW3950 and can use Motion Sync at 8,000 Hz.
• Glass Mode is available only on PAW3950 models.
• Sensor angle tuning, maximum sensor FPS, and lift-off LED control are limited to v2 models.
• Polling changes are blocked while Glass Mode controls the polling divider.

Config safety

• Updates continue to start from a fresh config read and change only documented fields.
• Reserved bytes are preserved, including unknown button mappings until they are replaced.
• Config frames are checked for valid status, stage count, polling divider, and CPI.
• Writes now require an ACK and are followed by a config readback.

Tests

• npm test
• npm run build
• git diff --check

Unit tests cover:

• Product profiles and sensor capability flags
• CPI ranges and model-specific quantization
• Normal and Glass Mode LOD lists
• BCD firmware version parsing
• Button control and mapping offsets
• Button action encoding and decoding

Hardware testing

The protocol and UI changes were tested on OP1 8K v2 hardware running firmware V1.07.

• OP1 8K
• XM2 8K
• OP1 8K Purple Frost
• OP1 8K v2 (firmware V1.07)
• XM2 8K v2

Suggested smoke test for each available model:

• Read the current config and firmware version.
• Change polling, CPI, active CPI stage, and LOD.
• Toggle each supported sensor option.
• Change multiclick and button mappings, then verify the physical controls.
• Reload the page and confirm that stored values are read back correctly.

Notes

• The 125 Hz, 250 Hz, and 500 Hz options use the same 8,000/divider formula as the higher rates. These rates are not exposed by the stock Endgame Gear tool.
• Stage LED color and enable bytes are preserved but are not exposed as controls.
• The UI waits for the write ACK and config readback before displaying the new value. Optimistic UI updates can be handled separately.