Add public validation case: STPST5H100 power Schottky diode

[lisiqi1983]

Goal: add a public validation case for STPST5H100 so extraction and diode model benchmarks cover a vendor page with an available SPICE model.

Suggested steps:

• Add a case entry or golden case under validation/.
• Record public source URL, expected ratings, VF point, capacitance/recovery fields when available.
• Run datasheet2spice score-case on the resulting project JSON.
• Run datasheet2spice benchmark-model for diode-basic and diode-abm-dynamic.

Do not commit vendor PDF or SPICE model files unless redistribution is explicitly allowed.