Feature Request: Expose token usage breakdown in statusline JSON

Feature Request: Expose token usage breakdown in statusline JSON

The /context command shows a detailed token breakdown by category (system prompt, MCP tools, messages, memory files, etc.), but this data isn't available in the statusline JSON input.

Current state

• Statusline JSON only provides total_input_tokens, total_output_tokens, context_window_size
• /context shows per-category breakdown (e.g., "MCP tools: 1.3k tokens (0.6%)")

Request

Add a token_breakdown object to the statusline JSON:

"token_breakdown": {
  "system_prompt": 3100,
  "system_tools": 18300,
  "mcp_tools": 1300,
  "memory_files": 4600,
  "messages": 8,
  "custom_agents": 917
}

Use case

Custom statuslines could show MCP usage, warn when memory files are heavy, or display other context insights without users needing to run /context manually.