Subagent-aware stats and Claude diagnostics
Fixed the biggest stats correctness issue in the CLI by separating canonical main sessions from subagents while keeping token and cost totals intact.
- Claude and Codex session counts now distinguish main sessions from subagents instead of inflating headline session totals.
- Added `--claude-system` and `--claude-limits` commands for inspecting `~/.claude.json`, `~/.claude/usage-data`, cache freshness, and local rate-limit signals.
- Refined the web share surfaces again with restored legacy usage/wrapped balance, tighter activity hover layout, and cleaner host-aware share behavior.