Add sheet-symbol PDN overrides and multi-instance SMPS Vin inference

[cs42]

Summary

• Allow PDN_<Des>_* parameters on sheet symbols to override child-sheet PDN directives per PCB instance (e.g. different sink currents or regulator voltages for reused sheets).
• Bind overrides via SOURCEUNIQUEID path (preferred) or hierarchical-path / sheet-name fallback; support indexed channels and REPEAT slot forms (PDN_J1_I.N).
• Merge sheet-symbol value overrides onto PCB-ECO / Blanket directives for the same placement (no duplicate sources; clearer partial-coverage warnings).
• When repeated regulator sheets publish different PDN_V onto a shared local output name, expand that net per instance for SMPS Vin inference so rails do not collide or drop from the supply map; propagate along placed SERIES edges (including 2-pin autoinfer) and expand PDN_IN_P_NET per placement.

Motivation

Reusable child sheets are often placed several times on one board. The shared schematic can only hold one default PDN_* value, but real loads and rail voltages differ per placement. Editing each physical instance only in the FYPA viewer or via PCB ECO does not keep that intent in the schematic. Sheet-symbol overrides (PDN_<Des>_* on each sheet symbol) keep per-instance values in Altium.

Different per-placement regulator voltages on a shared local switch/output label then require instance-scoped supply-map keys and SERIES-aware Vin lookup; otherwise SMPS gain inference can fail for downstream regulators on the filtered rails.

Test plan

• uv run pytest tests/test_annotations.py -q
• Spot-check a project with ≥2 placements of the same child sheet and different PDN_<Des>_I (or _V) on each sheet symbol; confirm distinct directives per PCB instance
• Confirm UniqueID binding when present; hierpath fallback only when SOURCEUNIQUEID is empty
• Spot-check repeated regulator sheets with a shared local OUT name and a SERIES filter inductor; confirm downstream SMPS Vin / gain without “cannot infer input voltage”