[P1.5-S6-ARI-45] UC3 round 3 acceptance test + report addendum

[bjridicodes]

Ticket: P1.5-S6-07

Type: Execution | Est: 1.5d

Goal: AC-01 through AC-06 validated on all 10 UC3 incidents with full log retrieval — closes the round 2 UC3 gap and completes Phase 1.5.

Pre-conditions: P1.5-S5-03 (UC3 incidents in ServiceNow), P1.5-S6-06 (UC3 smoke test passing)

Scope:

• Update tests/acceptance/ground_truth.json: set logs_available: true for all 10 UC3 entries
• Run all 10 UC3 incidents through ARIA pipeline in tool mode and API mode
• Score AC-01 through AC-06 (AC-03 now fully evaluated — no N/A for UC3)
• Append results to tests/acceptance/report_round2.md as "UC3 Round 3 Addendum" section
• Update p1_5_roadmap.md Phase 1.5 completion criteria table — mark all 6 sprint criteria as complete

Acceptance criteria:

• AC-03 (log recall) ≥ 80% on UC3 incidents
• AC-04 (classification accuracy) ≥ 70% on UC3 incidents
• AC-05 (confidence score) 100% of UC3 notifications include confidence band
• Report addendum written, reviewed, and committed to main
• Phase 1.5 completion criteria in p1_5_roadmap.md marked all-green