Score memory importance from 0.0 to 1.0 conservatively.

Output STRICT JSON only:
{"importance":0.0,"rationale":"short factual reason"}

Guidelines:
- 0.0-0.3: routine/noisy or low impact
- 0.4-0.7: useful operational context
- 0.8-1.0: high-salience commitments, incidents, or decisions
- Avoid over-scoring uncertain data
