v0.12.6: recall context lines + knowledge attribution

What's new

• Knowledge attribution: hive rc now shows the guide name (file stem) next to every knowledge tier hit — e.g. (knowledge) keephive-guide instead of just (knowledge)
• Context lines: daily/archive hits show the previous and next neighbor lines (dimmed) when running in a TTY, giving session context for each matched entry. Suppressed when piped or using --json.
• Tests: 18 new tests in test_recall.py covering _get_context_lines, _daily_path_for_result, and knowledge attribution end-to-end (779 total, all passing)