[PM-36965] feat: Add SeederApi scene for migration cohort CSV-export testing

[cyprain-okeke]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-36965

📔 Objective

Adds MigrationCohortExportScene to the Seeder — the HTTP/API equivalent of the
PM-36965 SQL seed script — so QA and local environments can populate the Admin
Portal migration-cohort management table with a cohort ready to Export CSV,
without hand-running SQL.

Given a cohortName and orgCount, the scene creates (or reuses by name) a
migration cohort, then bulk-creates N inert placeholder organizations
(Enabled = false, no billing, no users) and their cohort assignments. Real
Organization rows are required because OrganizationPlanMigrationCohortAssignment
has a FK to Organization with a UNIQUE constraint on OrganizationId.

Usage (local, SeederApi on :5047):

POST /seed
{ "template": "MigrationCohortExportScene",
  "arguments": { "cohortName": "PM-36965 Export Test", "orgCount": 5000 } }

Optional args: migrationPathId (default 1; null = churn-only cohort),
namePrefix (default pm36965-seed-).

Implementation notes

• Organizations and assignments are bulk-inserted via LinqToDB BulkCopy (the same
  path BulkCommitter uses) to stay fast up to the [Range(1, 100000)] ceiling.
• BulkCopy bypasses the repository CreateAsync play-id tracking hook, so the
  scene records PlayItem rows itself. This lets DELETE /seed/{playId} tear the
  seeded organizations down (assignments cascade via FK). The emptied cohort row is
  not play-id tracked (PlayItem has no CohortId) and is removed by name.
• Local / non-prod only — the SeederApi refuses to run in production.

Testing

• Integration tests assert database persistence (cohort + orgs + assignments read
  back), cohort reuse-by-name, and one-PlayItem-per-org tracking for cleanup.
• Full SeederApi.IntegrationTest suite: 180/180 passing.

📸 Screenshots

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

Reviewed the new MigrationCohortExportScene SeederApi scene (single file, local/non-prod tooling). The scene builds a migration cohort plus N inert placeholder organizations and their cohort assignments, bulk-inserts them via LinqToDB BulkCopy inside a single EF transaction, and self-records PlayItem rows so DELETE /seed/{playId} can tear the data down. I verified the transaction/BulkCopy pattern matches UserRepository, the FK ON DELETE CASCADE on OrganizationPlanMigrationCohortAssignment confirms the documented cleanup behavior, and the keyset-export ordering rationale in the remarks is accurate.

Code Review Details

No code-level findings. The implementation follows established Seeder conventions (BulkCopy + await using transaction rollback, mapper-based Core→EF mapping, explicit SetNewId() where BulkCopy bypasses the repository COMB hook), and cohort reuse-by-name is consistent with the IX_OrganizationPlanMigrationCohort_Name UNIQUE constraint.

PR Metadata Assessment

• ❓ QUESTION: The Testing section states integration tests were added and "180/180 passing", but no test file is present in the diff and the branch history shows scene-specific tests were removed per Scenes owner guidance. Consider updating the description so the stated test coverage matches what ships.

[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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.40%. Comparing base (5e773db) to head (1fc872a).

Additional details and impacted files

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  Coverage   61.40%   61.40%           
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  Files        2227     2227           
  Lines       98345    98345           
  Branches     8894     8894           
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  Hits        60386    60386           
  Misses      35822    35822           
  Partials     2137     2137           

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