fix: Re-anchor gated-signing counter on uint8 wrap to keep cadence aligned

The gated-signing screen is meant to render every GATED_SIGNING_MAX_COUNT
(10) signing operations, gated by a uint8_t counter in N_storage.
Because 256 is not a multiple of 10, the natural uint8_t wrap shifts
the cadence: a display would land on sign #251, then nothing until
sign #257 (gap of 6 instead of 10), then the cycle is permanently
out of phase relative to its starting point.

Detect the wrap (`counter + 1 == 0` after `uint8_t` promotion) and
re-anchor the stored counter to 1, which forces a display on the
wrap-spanning signing operation and resumes the every-10th cadence
from a known phase. The wrap-adjacent interval is 5 signs instead
of 10, accepted as a one-time anomaly; every subsequent cycle is
exactly 10.

Note: the modulo expression itself (`counter % MAX == 1`) is
equivalent to the original `(counter - 1) % MAX == 0` for every
uint8_t value, because C integer promotions make `counter - 1`
signed (`-1 % 10 == -1`, not 255). The previous form was readable
and correct; the fix above addresses the genuine wrap-cadence drift
the previous form did not cover.

(cherry picked from commit 842d35d00896976263d10e55af20f6649872ea1f)