test : added unit tests for finding_intelligence fingerprint and evidence helpers

[tmdeveloper007]

Closes #2074.

Summary of What Has Been Done:

Added testing/backend/unit/test_finding_intelligence_fingerprint.py with 17 unit tests covering three functions in backend/secuscan/finding_intelligence.py.

Changes Made:

_fingerprint_score (8 tests): validated/exact/strong_fuzzy/fuzzy/family/none/unknown/missing metadata cases

_finding_kind_for (7 tests): validated_issue, observation category, suspected_issue (severity/CVE/cpe_correlation), low-severity observation, empty category

_typed_evidence (6 tests): dict/non-dict items, confidence clamping, base confidence fallback, observed_at default, label title-casing

Tests pass with python3 -m pytest --noconftest.

Impact it Made:

• Validates finding classification logic for deduplication and reporting
• Ensures evidence normalization is consistent across scanners

Note: This task is being handled by tmdeveloper007 — please assign to that account when picking it up.

[utksh1]

This branch stacks five distinct test submissions, including replacement of existing recency coverage, so it is not reviewable as one focused PR. Please reset it to one cohesive helper/test area, preserve existing coverage instead of rewriting it, and fix the failing backend-unit check. The older stacked PRs have been closed as superseded.

[utksh1]

This branch stacks five distinct test submissions, including replacement of existing recency coverage, so it is not reviewable as one focused PR. Please reset it to one cohesive helper/test area, preserve existing coverage instead of rewriting it, and fix the failing backend-unit check. The older stacked PRs have been closed as superseded.

[utksh1]

This branch is a stack of five unrelated test PRs and also reduces existing _recency_detail coverage. Please split it into independent branches from current main, preserve the existing recency tests, and fix the failing backend-unit check. The fingerprint cases must remain aligned with the current 0.0 unknown-strength behavior.