Add DonorPerfect as vendor #9

[shivamlalakiya]

DonorPerfect is a widely-used nonprofit fundraising CRM — a natural vendor #9 alongside CiviCRM (added in v0.4.0).

Follow the documented 6-file checklist in docs/adding-a-vendor.md. Register at Tier 3 (bootstrap — verify with real payloads), mirroring how Ellucian and CiviCRM were introduced.

Scope

• src/schema/master.ts — add DONORPERFECT to SourceSystemSchema
• src/utils/sourceSystem.ts + src/utils/driftCapture.ts — register slug + drift config
• src/mappers/donorperfect.ts — Zod payload schema + mapDonorperfectToMaster (copy src/mappers/civicrm.ts)
• src/mappers/resolve.ts + src/mappers/index.ts — wire the mapper
• src/config/webhookRoutes.ts — Tier 3 + HMAC (DONORPERFECT_WEBHOOK_SECRET, x-donorperfect-signature)
• samples/donorperfect-*.json + fixtures + unit/integration tests
• npm run validate passes

Do not change the ConstituentEvent schema shape (see docs/schema-governance.md). The pattern is fully worked in the CiviCRM and Ellucian commits.