Skill: Cleanup module should report findings to the user

[aureamunoz]

The cleanup module currently fixes leftover Spring artifacts silently. It should report what it found and what it did, so the user can understand what was missed by previous modules.

Expected output after cleanup:

• What was found (leftover imports, unused deps, stale config, etc.)
• What was auto-fixed vs what was left for the user
• Which module should have handled it (helps improve the skill over time)

This serves two purposes:

1. User feedback: transparency on what slipped through earlier modules
2. Skill improvement: if cleanup consistently catches the same patterns, it signals that a module needs to be updated

Ref: feedback from PR #310 review by @cmoulliard.