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

Adds TYPE_PROJECT_EMAIL_TEMPLATE to the GROUP_PROJECTS migration group so per-locale custom email templates are carried over during an Appwrite-to-Appwrite migration. The source side uses offset pagination against listEmailTemplates; the destination bypasses the SDK's SMTP guard via a direct read-then-merge write to the projects collection.

• EmailTemplate is a new resource class with a clean serialisation round-trip (body internally, message on the wire) and a getGroup() returning Transfer::GROUP_PROJECTS.
• exportEmailTemplates in Sources/Appwrite.php paginates with limit/offset and correctly terminates when a partial page is returned, but passes optional SDK response fields (senderName, senderEmail, replyToEmail, replyToName) directly to the string-typed constructor without null coalescing — unlike the matching defensive pattern in EmailTemplate::fromArray — which can throw a TypeError if the Appwrite API returns null for unset sender/reply-to values.
• createEmailTemplate in Destinations/Appwrite.php follows the same read-then-merge pattern as createServices and createProtocols, with purgeCachedDocument called after each write to keep sequential updates consistent.

Confidence Score: 3/5

The destination write path and the new resource class are solid, but the source export passes optional API fields directly to typed constructor parameters without null-coalescing, which can crash mid-migration for any project whose templates have no custom sender or reply-to values.

The null-coalescing gap in exportEmailTemplates means any template without a custom senderName, senderEmail, replyToEmail, or replyToName (i.e., one using Appwrite defaults) could cause a TypeError that aborts the migration for that project. The same defensive pattern is already applied in EmailTemplate::fromArray, so the fix is straightforward, but the bug is on the hot path of the export loop.

src/Migration/Sources/Appwrite.php — the exportEmailTemplates method around the new EmailTemplate(...) constructor call.

Important Files Changed

Filename	Overview
src/Migration/Resources/Templates/EmailTemplate.php	New resource class for email templates; clean implementation with correct serialisation round-trip (internal body ↔ API message). fromArray accesses id, templateId, and locale without null guards, which is consistent with other resource classes but relies on callers always supplying those keys.
src/Migration/Sources/Appwrite.php	Adds offset-paginated export for email templates. Optional SDK fields (senderName, senderEmail, replyToEmail, replyToName) are passed directly to the EmailTemplate constructor without null coalescing, unlike the defensive pattern used in fromArray, risking a TypeError if the SDK returns null.
src/Migration/Destinations/Appwrite.php	Adds createEmailTemplate via direct DB write with read-then-merge; pattern is consistent with createServices and createProtocols. Cache is purged after each write, ensuring sequential per-template writes read fresh data.
src/Migration/Resource.php	Adds TYPE_PROJECT_EMAIL_TEMPLATE constant and registers it in the GROUP_PROJECTS_RESOURCES list; straightforward additive change.
src/Migration/Transfer.php	Adds TYPE_PROJECT_EMAIL_TEMPLATE to both GROUP_PROJECTS_RESOURCES and the all-resources list; consistent with surrounding entries.

_{Reviews (1): Last reviewed commit: "Fold email templates into projects group..." | Re-trigger Greptile}