Replace scattered magic numbers with named layout constants (_LABEL_OFST,
_NET_LABEL_FONTSIZE, _PARALLEL_PATH_SPACING, etc.) for consistent spacing.
Add "input_up" path classification that routes base/gate bias paths to
VCC left-then-up with local Vdd symbols, preventing wire crossings with
collector/drain vertical paths. Add _choose_label_side() for smart
alternating label placement and _sort_parallel_paths() to draw longest
chains closest to the device body.
Fix PNP/PFET polarity handling: supply terminal stub direction now
matches device polarity instead of always drawing upward.
Vertical chain label improvements:
- valign='bottom' for down-going chains pushes labels above midpoint
- Gap wire (0.5 units) before ground/Vdd terminators prevents overlap
- Minimum component length (_VERT_CHAIN_MIN_LEN) for readable labels
- valign='center' on device body and horizontal-turn labels
Ryan Malloy
b8b83fd282