Add efficiency metrics to classify_sessions() output #79

Problem

classify_sessions() categorizes sessions (debugging, development, research, maintenance, mixed) but doesn't include efficiency metrics. This makes it hard to answer "which session types burn the most context?"

Proposed Solution

Add efficiency fields to each session's classification output:

{
    "session_id": "abc123",
    "category": "debugging",
    "compaction_count": 12,
    "total_bytes": 5200000,
    "files_read_multiple_times": 8,
    "burn_rate": "high"  # optional: simple high/medium/low based on compactions/hour
}

Value

Correlates session type with context efficiency, helping identify which kinds of work need better tooling or workflow changes.

Implementation

1. Join with efficiency data from get_session_efficiency() query
2. Add fields to output
3. Optionally compute a simple burn_rate indicator

Related

• Part of efficiency analytics improvements
• Complements Add efficiency metrics to analyze_trends() #78 (efficiency trends)