fix(ccusage): prefer bunx before npx

[dck]

Summary

This fixes rtk cc-economics when ccusage is not installed as a direct binary but is available through Bun. RTK previously hardcoded a direct ccusage binary first and npx second, which caused it to miss valid bunx ccusage setups and, in practice, select older or less capable ccusage builds (at least on my machine) than the user’s normal workflow. Separately, bunx is significantly faster than npx for one-off package execution. Users with Bun installed should get it as the first fallback before npx.

The improvement:
The change introduces layered runner selection for ccusage with this priority: direct binary → bunx → pnpm dlx → yarn dlx → npx. It also removes the interactive npx ccusage --help probe, which could add latency or hang-like behavior before the real command even ran.

How It Works

ccusage execution is now selected through a dedicated runner policy instead of ad hoc probing.

The new selection order is:

1. ccusage
2. bunx ccusage
3. pnpm dlx ccusage
4. yarn dlx ccusage
5. npx --yes ccusage

This is important for RTK because cc-economics depends on ccusage features and output shape, and different runners can resolve different installed versions in real user environments. In my local
investigation, bunx ccusage resolved a newer build than npx ccusage, and the older npx path did not support commands that RTK expects, such as weekly reporting.

Test plan

• cargo fmt --all --check — clean
• cargo clippy --all-targets — no new warnings
• cargo test ccusage — 14/14 pass
• Runner priority tests verify: binary > bunx > pnpm > yarn > npx
• None case tested when no runner is available

[dck]

@pszymkowiak could you please take a look at this small PR?

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