feat: complete pnpm scripts directly

[bingoYB]

Summary

• Suggest package.json scripts directly after pnpm and while typing a script name.
• Keep built-in pnpm commands and avoid duplicate entries when a script shares a built-in name.
• Reuse the existing script reader for pnpm run and keep its fallback behavior.

Closes #164.

Verification

• go test ./commands/js ./spec passed.
• go vet ./commands/js ./spec passed.
• git diff --check passed.
• Full go test ./... was attempted. It could not complete because downloading modernc.org/libc@v1.73.4 ended with unexpected EOF; the environment-dependent TestZoxideGenerator also failed because no zoxide history results were available.

[versenilvis]

lgtm, just fix lint