analog M4b-psp: the StrongARM comparator on PSP103 tables -- predict the decision threshold M4e now fits #10856

Goal

M4e (#10818, PR #10854) matches the golden run 30 of 31 only with two fitted numbers; one of them is a 6.7 mV decision offset. Put the comparator in at PSP103 level so the offset is predicted, not fitted: run M4b's StrongARM latch (specs/analog/sar_comparator.t27, multi-node Newton) on the PSP103 current tables of M3b (specs/analog/mos_psp103_data.t27, tt, scaled by each device's m and W) instead of the square law, and measure the decision threshold (the input difference at which it flips) and the decision time against ngspice + PSP103 with the golden deck's comparator subcircuit at TEMP 50.

Requirements

• FR-001: Reuse the M4b solver and the M3b tables by use (generalize in their home specs; no copies).
• FR-002: The predicted threshold is reported next to M4e's fitted 6.7 mV and the latch's own +2.5 to +3.1 mV seen in the golden run.

Scenarios

• Given +-2 mV and +-0.5 mV inputs at the golden common mode, When clocked, Then the sign matches ngspice + PSP103 and the decision time is within a named bound.
• Given a sweep of the input difference, When the flip point is found, Then it is within a named bound of ngspice's.
• Given the ss tables (negative control), When compared with ngspice tt, Then the check fails.

Boundary

• specs/analog/sar_comparator.t27 (or a new PSP103 variant spec beside it) and decks; no change to M4e's numbers in this issue.

Success Criteria

• t27c test-report 0 vacuous; threshold and decision time vs ngspice + PSP103 within named bounds; negative control fails.

Part of #10818

Success Criteria

• t27c specs/analog/sar_comparator.t27 exits 0 and reports comparator decision threshold within 0.5 mV of ngspice + PSP103 golden deck at TEMP 50
• t27c specs/analog/sar_comparator.t27 exits 0 and reports decision time within 10 ps of ngspice + PSP103 golden deck at TEMP 50 for ±2 mV and ±0.5 mV inputs at golden common mode
• t27c specs/analog/sar_comparator.t27 --negative-control exits non-zero when ss tables are compared against ngspice tt
• t27c test-report exits 0 with 0 vacuous tests