Progress-sync routing should record event provenance when the active issue differs

Observation (2026-09-08T13:12:46+00:00; source: post-commit event post_commit-64b029b835864e0a9bdce8a445e307b2): a progress-sync event may carry an originating issue key different from the explicitly inferred active issue. Preserve the event’s commit SHA and source provenance in the target issue update, and deduplicate by target issue + commit SHA before posting.