fix: execute installed CLI entrypoint

[rogerchappel]

Summary

• Resolve the CLI module and process.argv[1] through their real paths so npm's .bin symlink is recognized as the executable entrypoint.
• Treat a missing or unresolvable argv path as an import, keeping the package safe to load without invoking the CLI.
• Add a packed-install regression test covering --version, the default plan command, and side-effect-free import behavior.

Verification

• Tests or checks run: node --test test/cli.test.js; bash scripts/validate.sh; npm run release:check; git diff --check
• Manual review completed: reproduced the current packed binary returning no stdout before the fix and confirmed the packed binary returns 0.1.0 plus a non-empty one-file plan after the fix.

Risk Level

• Low
• Medium
• High

Notes: The change is limited to executable-entrypoint detection and one packed-install regression test. Public exports and CLI behavior are unchanged.

Rollback Plan

• Revert commit 92c3305 to restore the previous URL equality check and remove the regression test.

Human Decision Needed

• None
• Maintainer review
• Product/design decision
• Security/privacy review
• Other: