Add webhook migration support

[premtsd-code]

Summary

Stacks on #184. Adds webhook as a migrable resource.

• Source: Appwrite SDK Webhooks::list() (separate service from Project) with cursor pagination. Reports via reportIntegrations.
• Destination: direct dbForPlatform->createDocument('webhooks', ...) matching the upstream Webhooks::Create payload exactly.

Notes

• Resource::TYPE_WEBHOOK = 'webhook', placed in GROUP_INTEGRATIONS_RESOURCES.
• Carries through name, url, events, security (TLS), httpUser/httpPass (basic auth), and enabled.
• Signing secret regenerates: the SDK strips signatureKey on list responses (Webhooks/XList.php explicitly removeAttribute('signatureKey')). Destination generates a fresh bin2hex(random_bytes(64)) to match upstream's createWebhook default. Webhook receivers verifying signatures must be updated with the destination's new key.

[greptile-apps]

Greptile Summary

This PR introduces webhook migration support, adding Webhook as a migratable resource under the GROUP_INTEGRATIONS group. Source-side cursor-paginated export is wired through the existing Webhooks SDK service, and destination-side creation writes directly to dbForPlatform with a freshly-generated signatureKey (since the SDK strips it from list responses).

• New Webhook resource class (Resources/Settings/Webhook.php) exposes all webhook fields; getGroup() correctly returns GROUP_INTEGRATIONS, routing it to importIntegrationsResource on the destination.
• Source (Sources/Appwrite.php): exportWebhooks() follows the established cursor-pagination pattern and reportIntegrations counting is added alongside platforms and API keys.
• Destination (Destinations/Appwrite.php): createWebhook() mirrors the createPlatform/createApiKey pattern — idempotency check on projectInternalId + name, DB insert, cache purge.

Confidence Score: 5/5

The change is self-contained, follows established patterns for Platform and ApiKey migration, and the group/routing wiring is correct. Safe to merge.

The routing, pagination, dedup, and cache-purge logic all mirror existing sibling resources with no divergence. The only finding is a cosmetic comment-placement nit in Resource.php.

No files require special attention beyond the minor comment-section placement in Resource.php.

Important Files Changed

Filename	Overview
src/Migration/Resources/Settings/Webhook.php	New Webhook resource class; correctly returns GROUP_INTEGRATIONS from getGroup(), implements all required accessor methods, fromArray, and jsonSerialize.
src/Migration/Sources/Appwrite.php	Adds exportWebhooks() with cursor pagination and reportIntegrations counting; pattern mirrors existing exportProjectVariables(); exportGroupIntegrations correctly dispatches webhook export.
src/Migration/Destinations/Appwrite.php	Adds TYPE_WEBHOOK to supported resources and importIntegrationsResource switch; createWebhook() writes to dbForPlatform with a freshly-generated signatureKey and purges the project cache.
src/Migration/Resource.php	TYPE_WEBHOOK constant added under the // Settings comment, but the resource's group is GROUP_INTEGRATIONS — inconsistent placement that could mislead readers.
src/Migration/Transfer.php	TYPE_WEBHOOK correctly added to GROUP_INTEGRATIONS_RESOURCES and ALL_PUBLIC_RESOURCES.

_{Reviews (7): Last reviewed commit: "Webhook resource reports integrations gr..." | Re-trigger Greptile}

[abnegate]

Let's group this with integrations