OM-334 Add lab reference range flag helper

[Ispagiytiy]

Pull Request

Description

Adds deterministic lab reference range parsing and abnormal flag derivation helpers for numeric lab ranges, with focused unit tests and a changelog entry.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Test addition/improvement

Changes Made

• Added parse_reference_range() for numeric lab reference range strings such as 135-145, 0.5 - 1.2, <5, and >10.
• Added derive_abnormal_flag() to return low, normal, high, critical, or unknown from a value, parsed reference range, and optional explicit flag.
• Normalized explicit H and L flags to high and low before numeric range comparison.
• Added unit tests for range parsing, one-sided ranges, explicit flag precedence, low/normal derivation, non-numeric values, and invalid range inputs.

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this change with different models/inputs

Documentation

• I have updated the documentation accordingly
• I have added docstrings to new functions/classes
• I have updated the CHANGELOG.md

Code Quality

• I ran make format, make lint, and make format-check
• For Swift/OpenMedKit changes, I ran make format-swift and make lint-swift
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

Dependencies

• I have not added any new dependencies
• OR I have added new dependencies and they are justified because: ____

Checklist

• I have read the contributing guidelines
• My commits have clear, descriptive messages
• I have squashed/organized my commits appropriately

Related Issues

Closes #524

Screenshots/Examples

N/A - no UI changes. Covered by unit tests in tests/unit/clinical/test_lab_values.py.

[maziyarpanahi]

Thank you @Ispagiytiy. I reviewed this against #524 / OM-334 and added one maintainer follow-up merge commit: Merge master into lab values helper.

What I changed:

• resolved the CHANGELOG.md conflict against current master while preserving the lab-values entry;
• kept the already-merged cardiology label-map changes from master in the PR branch;
• added the advisory disclaimer that derived lab flags are heuristic and not a substitute for source lab flagging or clinical review;
• made value parsing stricter so arbitrary strings with embedded numbers return unknown rather than guessing;
• added normal/critical explicit-flag aliases and broader tests for decimal ranges, one-sided inclusive bounds, explicit flags, and unparseable parsed ranges.

Verification on the current PR checkout:

• PYTHONPATH=/private/tmp/openmed-pr-560 /Users/maziyar/Developer/openmed/.venv/bin/python -m pytest tests/unit/clinical/test_lab_values.py tests/unit/ner/test_label_map_consistency.py -q -> 73 passed
• /Users/maziyar/Developer/openmed/.venv/bin/ruff check openmed/clinical/lab_values.py tests/unit/clinical/test_lab_values.py openmed/core/model_registry.py tests/unit/ner/test_label_map_consistency.py CHANGELOG.md -> passed
• /Users/maziyar/Developer/openmed/.venv/bin/ruff format --check openmed/clinical/lab_values.py tests/unit/clinical/test_lab_values.py openmed/core/model_registry.py tests/unit/ner/test_label_map_consistency.py -> passed

I also copied the labels from #524 onto the PR. The branch is mergeable with no conflicts; GitHub has not attached hosted checks to the new head commit yet, so I verified the touched behavior locally.