Architecture decision records

• 0001 Standard-library core, optional extras
• 0002 ACH ranks by least inconsistency, with confidence caps
• 0003 Every extracted fact carries a source span
• 0004 Leave-one-report-out attribution evaluation
• 0005 Louvain on a kNN-sparsified Diamond event graph
• 0006 Hand-built STIX 2.1 export validated with python-stix2
• 0007 Learned grade map and an optional support-aware ranking