fix(reports): do not report success when every model was skipped

[Eljees]

Fixes #218

When every model in the scan was skipped, the console report still printed the success line:

--- Summary ---

 No issues found! 🎉

--- Skipped ---

Total skipped: 1 - run with --show-skipped to see the full list.

"No issues found" is only true of files that were actually scanned, and the skip notice sits below the
line most people stop reading at.

ConsoleReport now distinguishes the two cases:

 No issues found in the scanned files, but 1 file(s) were skipped and not scanned.

The cheerful line stays exactly as it was when nothing was skipped, so a clean scan looks the same as before.
Exit codes are untouched — this PR only changes what the summary says.

Tests

tests/test_reports.py (new): with a skipped file the output must not contain "No issues found!" and must
mention the skipped count; with nothing skipped the original line must still appear.

PYTHONPATH=/src python -m pytest tests/test_reports.py tests/test_cli.py -q   ->  3 passed

AI-assisted (LLM used for drafting); the change and the test run are mine.