Report concise scope counts with analysis results

[stef-k]

Closes #94

Summary

• Report selected, analyzed, inapplicable, and all-guard-excluded file totals for every completed analysis.
• Add the exact compact human summary and additive JSON scope object without changing states, findings, policies, or exit behavior.
• Reuse existing enabled-guard applicability and shared provider work without adding telemetry or generalized statistics infrastructure.
• Document the counting model and add the feature to the Unreleased changelog.

Validation

• python -m unittest tests.test_scope_counts — 3 passed.
• python -m unittest discover -s tests — 288 passed.
• Empty, mixed, and REVIEW public CLI probes — passed.
• git diff --check main...HEAD — passed.
• Code Guard exact changed-file review — only retained non-blocking findings in existing surfaces.