Add Email Templates migration

[premtsd-code]

Summary

• Adds TYPE_PROJECT_EMAIL_TEMPLATE to GROUP_PROJECTS_RESOURCES for migrating the project's per-locale email template overrides.
• Source (Sources/Appwrite) reads templates via Project::listEmailTemplates (offset-paginated; not cursor) and emits one EmailTemplate resource per (type, locale).
• Destination (Destinations/Appwrite) replays them via Project::updateEmailTemplate for each entry.
• No new group: per the abnegate review on feat(migration): add project-level resource migrations #186, project's own email copy is just another per-project singleton — it belongs in GROUP_PROJECTS alongside PROJECT_VARIABLE / PROJECT_PROTOCOLS / PROJECT_LABELS / PROJECT_SERVICES.

Test plan

• CI lints + tests green
• E2E testAppwriteMigrationEmailTemplates (in appwrite/appwrite) passes

[greptile-apps]

Greptile Summary

This PR adds email template migration support (TYPE_PROJECT_EMAIL_TEMPLATE) to the Appwrite-to-Appwrite migration path, covering per-locale overrides for all template types in a project.

• Source (Sources/Appwrite.php): offset-paginates listEmailTemplates (cursor pagination is unavailable for this endpoint) and emits one EmailTemplate resource per (templateId, locale) pair; the report count uses total: true, which is confirmed valid by the SDK docs.
• Destination (Destinations/Appwrite.php): writes templates directly to the projects document via dbForPlatform rather than the SDK's updateEmailTemplate (which requires custom SMTP to be enabled), using the same read-modify-write + cache-purge pattern already established by createServices and createSMTP.
• Resource (Resources/Templates/EmailTemplate.php): new class with typed getters, fromArray with null-coalescence guards, and jsonSerialize mapping body ↔ message consistently with the SDK wire format.

Confidence Score: 5/5

Safe to merge — the new code follows established patterns throughout the codebase and no correctness issues were found.

The destination write uses the same read-modify-write + cache-purge pattern as createServices and createSMTP, proven correct for sequential per-resource processing. The total: true named argument on listEmailTemplates is confirmed valid by the Appwrite PHP SDK docs. Null-coalescence guards in fromArray are consistent with the model's guaranteed-empty-string wire format.

No files require special attention.

Important Files Changed

Filename	Overview
src/Migration/Resources/Templates/EmailTemplate.php	New resource class modelling one (templateId, locale) pair; follows the existing Resource contract correctly with fromArray, jsonSerialize, and typed getters.
src/Migration/Sources/Appwrite.php	Adds exportEmailTemplates with offset pagination and report count via listEmailTemplates(total: true); pattern matches other GROUP_PROJECTS exporters and the total: true named arg is confirmed valid by the SDK docs.
src/Migration/Destinations/Appwrite.php	Adds createEmailTemplate using the established read-modify-write + cache-purge pattern (identical to createServices and createSMTP); direct DB write correctly bypasses the SMTP-gated SDK endpoint.
src/Migration/Resource.php	Adds TYPE_PROJECT_EMAIL_TEMPLATE constant and registers it in GROUP_PROJECTS_RESOURCES; consistent with other project-level resource types.
src/Migration/Transfer.php	Adds the new type to both GROUP_PROJECTS_RESOURCES and the global resource list; correctly placed alongside other per-project singletons.
tests/Migration/Unit/Adapters/MockDestination.php	Registers TYPE_PROJECT_EMAIL_TEMPLATE in the mock's supported-resources list; minimal, correct change.
tests/Migration/Unit/Adapters/MockSource.php	Registers TYPE_PROJECT_EMAIL_TEMPLATE in the mock's supported-resources list; minimal, correct change.

_{Reviews (4): Last reviewed commit: "Register TYPE_PROJECT_EMAIL_TEMPLATE in ..." | Re-trigger Greptile}