perf: investigate diffImpact latency regression in 3.9.2 (WASM +94%, native +28%)

[carlos-alm]

Context

PR #900 records query benchmarks for v3.9.2 showing a significant diffImpact latency regression:

• WASM: 6.5ms → 12.6ms (+94%)
• Native: 7.5ms → 9.6ms (+28%)

This reverses improvements made in 3.9.1 (which had brought both values down 18-19%).

Investigation areas

• domain/queries.ts — diffImpact query path
• domain/graph/resolve.ts — import resolution changes
• Changes between 3.9.1 and 3.9.2 that touch the query or resolution layers

Source

Flagged by Greptile review on PR #900.