Improve localization evidence without blocking coding sessions

[zzet]

Summary

• improve localization evidence selection, causal/complementary candidates, provenance, and Evidence/response alignment
• make localization completion advisory in real coding sessions; there is no benchmark-only hard tool gate
• preserve focused syntactic anchors and reject/demote unsupported PRIMARY rows
• add regression coverage for recovery, tool presets, session safety, artifact intent, causal localization, and pricing

Validation

• targeted localization and session-safety tests pass
• internal/mcp and internal/hooks suites passed before the final focused ranking adjustments; full/race validation will be rerun before readiness