Need fix `grep` savings to much lower

Problem

rtk gain shows much lower savings for rtk grep

On my session, rtk gain reported:

• Command: rtk grep
• Count: 94
• Saved: 3.3M
• Avg%: 17.9%

But the README advertises roughly -80% savings for grep / rg.

Why this is confusing

This makes it look like rtk grep underperforms badly in real usage, even though the likely issue is broader:

• Claude Code prefers native tools like Grep, Read, and Glob
• those native tools bypass the Bash hook
• RTK therefore does not see or compress much of the actual search workload
• rtk gain ends up showing a result that users can easily interpret as “grep savings are poor”

Expected behavior

One of these should happen:

1. rtk gain / rtk discover should show “reachable vs unreachable” search activity
2. the UI should otherwise make it clearer that this is a tooling-path limitation, not necessarily an rtk grep filter-quality problem

Actual behavior

rtk gain shows low rtk grep savings without enough context to explain why.

Environment

• RTK version: 0.28.2
• OS: [26.3 (25D125)
• Agent/client: OpenCode & Codex (CLI & desktop)
• Hook installed: yes