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 adds webhook as a migratable resource, implementing both the source export (via Appwrite\\Services\\Webhooks::list() with cursor pagination) and destination import (writing directly to dbForPlatform). The implementation mirrors the existing ProjectVariable migration from PR #184.

• Source (Sources/Appwrite.php): adds exportWebhooks() and webhook counting in reportSettings, using the same total === 0 / count < batchSize pagination pattern as exportProjectVariables.
• Resource (Resources/Settings/Webhook.php): new resource class carrying name, url, events, security, httpUser/httpPass, and enabled; signatureKey is intentionally omitted.
• Destination (Destinations/Appwrite.php): createWebhook() writes to dbForPlatform, regenerates signatureKey via bin2hex(random_bytes(64)), and purges the project cache.

Confidence Score: 5/5

Safe to merge; the changes are a well-scoped addition that mirrors the established ProjectVariable migration pattern throughout.

The webhook migration is a faithful extension of the existing ProjectVariable pattern: source pagination, destination deduplication, and dbForPlatform writes are all consistent with the surrounding code. The deliberate signatureKey regeneration is correctly documented and mirrors Appwrite's own createWebhook behavior. No functional regressions are introduced in shared code paths.

No files require special attention.

Important Files Changed

Filename	Overview
src/Migration/Resources/Settings/Webhook.php	New resource class; clean implementation with typed properties, fromArray, jsonSerialize, and accessors matching the ProjectVariable pattern.
src/Migration/Sources/Appwrite.php	Adds exportWebhooks() and webhook reporting to reportSettings; pagination logic mirrors exportProjectVariables exactly.
src/Migration/Destinations/Appwrite.php	Adds createWebhook() using dbForPlatform with name-only dedup and fresh signatureKey generation; name-only dedup limitation was already flagged in previous review threads.
src/Migration/Resource.php	Adds TYPE_WEBHOOK constant and registers it in the appropriate group.
src/Migration/Transfer.php	Adds TYPE_WEBHOOK to GROUP_SETTINGS_RESOURCES and the flat resource list, consistent with the Webhook class and source/destination.

_{Reviews (4): Last reviewed commit: "Merge remote-tracking branch 'origin/add..." | Re-trigger Greptile}

[greptile-apps]

Name-only dedup silently drops duplicate-named webhooks

The idempotency check matches on projectInternalId + name, but Appwrite does not enforce unique webhook names within a project. If the source project has two webhooks sharing the same name (e.g. "My Webhook") pointing to different URLs, the second one is silently skipped with "Webhook already exists" — resulting in undetected data loss. Adding url to the dedup query would distinguish same-named webhooks and avoid the false positive.