REQ-026 — Per-channel ADC current readback functional on all 8 channels

The per-channel ADC shunt current readback shall function on all 8 LED current channels.

Carried from R0 design log DL-001 (resolved): CH7 ADC shunt readback was non-functional because R111 on ESH10000584 was incorrectly mounted (should be NM, like R112–R116) and back-drove the ADC6/CH7 node low. R1 design shall ensure R111 is not-mounted so all 8 channels read back correctly without rework.

All 8 LED current channels return a valid, monotonically tracking ADC current readback when driven; no channel reads stuck/low. R111 on ESH10000584 confirmed NM in the R1 build.