Fix redline analysis routing priority

[epowell40]

Summary

• keep explicit read-only redline analysis out of deterministic MEP and semantic AEC preemption
• cover both real non-streaming and streaming dispatch entrypoints
• preserve the deterministic analysis-only terminal lane

Verification

• public backend: 972 passed, 3 skipped
• private mirror: 1336 passed
• focused redline live-gap: 8 passed in each mirror
• live Sidecar run against the Snowdon test model persisted grounded AEC evidence with zero planned Revit actions and no model file timestamp/length change