fix: interpolate output paths in completion logs

[johnjheejin]

Summary

• interpolate the generated HTML viewer path in its completion log
• interpolate the generated AI context guide path in its completion log
• add CLI regression coverage for both resolved paths and the escaped placeholder

Root cause

The two template literals escaped ${outPath}, so the CLI printed the placeholder text instead of each generated artifact's absolute path.

User impact

Completion logs now point directly to index.html and ai_context_guide.txt, making the generated artifacts easy to locate.

Validation

• npm test (9 tests passed)
• node --check quarkify.mjs
• git diff --check