Function cmd_memory_context 

pub fn cmd_memory_context(beans_dir: &Path, json: bool) -> Result<()>

Output memory context for session-start injection.

When bn context is called without a bean ID, it returns relevant memories:

1. WARNINGS — stale facts, past failures (never truncated)
2. WORKING ON — claimed beans with attempt history
3. RELEVANT FACTS — scored by path overlap, dependencies
4. RECENT WORK — closed beans from last 7 days