[Suggestion] Add tool efficiency analysis #38

Is your feature request related to a problem? Please describe.
The plugin shows tool token usage and definitions separately, but does not reveal which tools are slow, failing, oversized, overused, or defined without being called.

Describe the solution you'd like
Add per-tool call counts, output/input averages, latency, failures, definition size, and unused-tool recommendations.

Additional context
Execution order: 6, after #37. Combine server-captured definitions with turn telemetry while marking attribution as approximate when necessary.