Instead of hardcoding confidence: 1.0, compute it at ingestion time using
the same resolution tier system that CALLS edges already use.
Heritage edges (EXTENDS, IMPLEMENTS):
- resolveHeritageId now returns { id, confidence } using TIER_CONFIDENCE
- Same-file → 0.95, import-scoped → 0.9, global → 0.5
- Edge confidence = geometric mean of source and target confidence
(principled for partially-correlated cross-scope estimates, per
Dillig et al. POPL 2011 and Dempster-Shafer theory)
MRO edges (OVERRIDES):
- MRO-ordered → 0.9, class method wins → 0.95
- Single interface → 0.85, ambiguous/unresolved → 0.5
IMPORTS and CONTAINS intentionally keep 1.0 (deterministic).
Closes#412
