Generate courtyards for parameterized passive footprints

[AnasSarkiz]

Summary

• emit a courtyard for parameterized resistor, capacitor, diode, and LED footprint strings
• derive custom-footprint bounds from copper, optional body dimensions, and the full stroked silkscreen
• preserve every existing named-package silkscreen and authored courtyard unchanged
• add four PCB snapshots with courtyards visible
• add no fixed clearance expansion

Why

Parameterized passive footprint strings emitted pads and silkscreen but no courtyard. They now receive a geometry-derived rectangular courtyard without redesigning existing footprints or changing KiCad-compatible named-package courtyards.

Validation

• 527 tests pass
• all affected named-package courtyard parity checks remain at 100%
• build passes
• Biome check passes
• resistor, capacitor, diode, and LED courtyard snapshots visually inspected

The derived custom courtyard is a geometry envelope; it does not claim an additional assembly-clearance margin.