feat: add PowerBI dashboard views migration

[Warren-Pitterson]

Description

Adds SQL views via EF migration to replace PowerBI's direct table access for improved security.

Context

https://nhsd-jira.digital.nhs.uk/browse/DTOSS-11764

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[github-actions]

Unit Test Results

✔️ Tests 887 / 887 - passed in 67.6s
📝 Coverage 46.44%
📏 4528 / 10009 lines covered 🌿 1095 / 2100 branches covered
🔍 click here for more details

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud