test(memory): raise patch coverage from 83% to 98% on error_recovery fixes

fix(memory): collapse and decay error_recovery patterns in MEMORY.md

test(learn): cover flush_to_file, backend edge cases, and hydrate/bump error paths

fix(learn): persist real evidence_count and bump on re-sighting

feat(learn): live flush of traffic patterns to agent-native context files

Fix ruff lint errors in test files

feat: add live traffic learning + cross-agent memory writers (--learn flag)