Add session learning miner

[saphid]

Summary

• add codex-lesson-miner/clm for deterministic phase-span and learning-card mining
• support Codex, Claude Code, Pi, and generic JSON/JSONL session sources
• add autoresearch runner plus OpenSpec change and fixture coverage

Validation

• PYTHONPATH=src python3 -m unittest discover -q
• npm test
• openspec validate add-session-learning-miner --strict
• real scans over local Codex/Claude/Pi and copied LXSO1 Codex/Pi/Hermes data

Notes

• Reports and copied LXSO1 sessions stay ignored under reports/.
• Claude -p review was attempted but local Claude Code is session-limited until 2am Australia/Sydney; Codex subagent review findings were addressed.