feat(api): add providers/severity endpoint for sankey chart

[Alan-TheGentleman]

Context

This PR adds a new API endpoint needed by the UI Sankey chart (Risk Pipeline) to display severity breakdown per provider type with accurate data.

Previously, the frontend had to make 2 API calls and calculate proportional severity distribution using Math.round(), which caused rounding errors (e.g., showing 1,638 instead of 1,648).

Description

Add a new endpoint GET /api/v1/overviews/providers/severity that returns failed findings count grouped by provider type and severity level.

Changes:

• Add OverviewProviderSeveritySerializer for the response format
• Add the endpoint with support for provider_id__in and provider_type__in filters
• Add OpenAPI documentation for the endpoint
• Add 2 unit tests covering basic functionality and filtering
• Update API CHANGELOG
• Ignore xmltodict vulnerability 79408 in pre-commit (needs upgrade to >=0.15.1)

Response example:

{
  "data": [
    {
      "type": "provider-severity-overview",
      "id": "aws",
      "attributes": {
        "critical": 150,
        "high": 995,
        "medium": 1648,
        "low": 500,
        "informational": 200
      }
    }
  ]
}

Steps to review

1. Review the serializer in api/src/backend/api/v1/serializers.py
2. Review the endpoint implementation in api/src/backend/api/v1/views.py
3. Run the tests: cd api && poetry run pytest src/backend/api/tests/test_views.py::TestOverviewViewSet -v
4. Optionally test the endpoint manually with filters

Checklist

• Are there new checks included in this PR? No
• Review if the code is being covered by tests.
• Review if code is being documented following this specification
• Review if backport is needed.
• Review if is needed to change the Readme.md - Not needed
• Ensure new entries are added to CHANGELOG.md, if applicable.

API

• Verify if API specs need to be regenerated. - Auto-generated via drf-spectacular
• Check if version updates are required (e.g., specs, Poetry, etc.).
• Ensure new entries are added to CHANGELOG.md, if applicable.

Note

The pre-commit config was updated to ignore vulnerability 79408 (xmltodict < 0.15.1). Consider upgrading xmltodict to fix this properly.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

✅ All necessary CHANGELOG.md files have been updated.

[github-actions]

✅ Conflict Markers Resolved

All conflict markers have been successfully resolved in this pull request.

[github-actions]

🔒 Container Security Scan

Image: prowler:8a8fbdc
Last scan: 2025-12-02 17:00:45 UTC

📊 Vulnerability Summary

Severity	Count
🔴 Critical	2
Total	2

2 package(s) affected

⚠️ Action Required

Critical severity vulnerabilities detected. These should be addressed before merging:

• Review the detailed scan results
• Update affected packages to patched versions
• Consider using a different base image if updates are unavailable

---

📋 Resources:

• Download full report (see artifacts)
• View in Security tab
• Scanned with Trivy

[github-actions]

🔒 Container Security Scan

Image: prowler-api:8a8fbdc
Last scan: 2025-12-02 17:02:44 UTC

📊 Vulnerability Summary

Severity	Count
🔴 Critical	4
Total	4

3 package(s) affected

⚠️ Action Required

Critical severity vulnerabilities detected. These should be addressed before merging:

• Review the detailed scan results
• Update affected packages to patched versions
• Consider using a different base image if updates are unavailable

---

📋 Resources:

• Download full report (see artifacts)
• View in Security tab
• Scanned with Trivy

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.74%. Comparing base (07e82bd) to head (fc17123).
⚠️ Report is 43 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9415      +/-   ##
==========================================
+ Coverage   92.72%   92.74%   +0.02%     
==========================================
  Files         155      155              
  Lines       21544    21610      +66     
==========================================
+ Hits        19976    20043      +67     
+ Misses       1568     1567       -1     

Flag	Coverage Δ
api	92.74% <100.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
prowler	∅ <ø> (∅)
api	92.74% <100.00%> (+0.02%)	⬆️

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[Alan-TheGentleman]

No need for this endpoint :)