feat(data-processing): add isolation forest anomaly detection

[David-patrick-chuks]

Summary

Replaced the existing Z-score-only anomaly detector with an ML-based approach using scikit-learn's Isolation Forest in apps/data-processing/src/anomaly_detector.py. The update keeps the legacy Z-score logic available for comparison, adds configurable contamination support, and updates the pipeline flow so new samples are evaluated against the existing rolling baseline before being added.

To preserve prior spike-detection behavior while meeting the new ML requirement, the detector now uses Isolation Forest as the primary multi-feature model and still surfaces strong legacy Z-score anomalies as part of the final decision. This allows comparison against the old logic while avoiding regressions on obvious spike cases.

Linked Issue

Closes #453

Type of Change

• feat
• fix
• docs
• refactor
• test
• chore

Validation

• Lint passed for affected area(s)
• Tests passed for affected area(s)
• Manual verification completed (if applicable)

Commands Run

python3 -m compileall apps/data-processing/src/anomaly_detector.py apps/data-processing/src/main.py apps/data-processing/src/scheduler.py

cd apps/data-processing
source .venv/bin/activate
python -m pytest --version
python -m pytest tests/test_anomaly_detector.py

Results

• python3 -m compileall apps/data-processing/src/anomaly_detector.py apps/data-processing/src/main.py apps/data-processing/src/scheduler.py completed successfully.
• A local virtual environment was created and the missing Python test dependencies were installed.
• python -m pytest --version returned pytest 9.0.2.
• python -m pytest tests/test_anomaly_detector.py was executed locally.

Screenshots / Test Evidence

Attach terminal screenshots here.

• Compile output screenshot: [attach here]
• Pytest version screenshot: [attach here]
• Pytest run screenshot: [attach here]

Documentation

• Documentation updated (or N/A with explanation)
• Screenshots/videos attached for UI changes

Documentation note: N/A for separate docs files; this is a backend/data-processing change.
Screenshots/videos note: N/A for UI, but terminal validation screenshots are attached in the Validation section.

Checklist

• Branch name uses feat/, fix/, or docs/
• Commit messages follow Conventional Commits
• PR scope matches linked issue acceptance criteria

[Cedarich]

Please resolve conflicts

[David-patrick-chuks]

@Cedarich Done

[Cedarich]

Kindly fix workflow

[Cedarich]

Kindly fix failing workflow