Add Custom Domains migration

[premtsd-code]

Summary

• Adds a new GROUP_DOMAINS resource group with Resource::TYPE_RULE for migrating custom-domain proxy rules.
• Source (Sources/Appwrite) lists rules via the console SDK's Proxy service, paginated with cursor.
• Destination (Destinations/Appwrite) dispatches to the SDK's four proxy-rule create endpoints (createAPIRule, createFunctionRule, createSiteRule, createRedirectRule) based on the rule's type + deploymentResourceType.
• Auto-generated .appwrite.network rules are skipped — they're recreated automatically when the parent Function/Site is migrated.
• Cross-project domain uniqueness conflicts (409) are surfaced as STATUS_WARNING rather than aborting the migration, since the source must release the domain first.
• Stubbed exportGroupDomains in Firebase / NHost / JSON / CSV sources to satisfy the new abstract method.

Test plan

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

[greptile-apps]

Greptile Summary

This PR introduces custom-domains migration by adding a new GROUP_DOMAINS group backed by a Rule resource, wiring up paginated export from the Appwrite proxy source, and dispatching to the four proxy-rule create endpoints (createAPIRule, createFunctionRule, createSiteRule, createRedirectRule) in the destination. Auto-generated .appwrite.network rules are skipped at the destination, and 409 conflicts surface as warnings rather than hard failures.

• Rule resource class, GROUP_DOMAINS/GROUP_DOMAINS_RESOURCES constants, and exportGroupDomains abstract method added across source/destination/transfer layers; all existing sources receive a "Not Implemented" stub.
• exportRules uses cursor-based pagination following the same pattern as existing exportUsers/exportTeams methods; createRule branches on type (api, redirect, deployment) with appropriate skip/warning paths.

Confidence Score: 5/5

Safe to merge; the new domains migration path is well-isolated and follows established patterns throughout the codebase.

No new defects are introduced. The source export, resource model, and destination dispatch are all correctly wired. The only pre-existing gap (GROUP_SETTINGS absent from extractServices) predates this PR and is not made worse here. The redirect-rule fallback for empty deploymentResourceType was flagged in a prior review cycle.

src/Migration/Destinations/Appwrite.php — specifically the redirect-rule branch (already discussed in a previous review round).

Important Files Changed

Filename	Overview
src/Migration/Resources/Domains/Rule.php	New Rule resource class for custom-domain proxy rules; clean implementation with typed properties, complete getters, and consistent fromArray/jsonSerialize pair.
src/Migration/Sources/Appwrite.php	Adds exportGroupDomains/exportRules with cursor pagination; logic is consistent with existing patterns but reportDomains counts all rules (including skipped auto-generated ones), which may overstate expected migration totals in progress reports.
src/Migration/Destinations/Appwrite.php	Adds importDomainsResource/createRule; redirect-rule branch unconditionally passes resourceId+resourceType even when deploymentResourceType is empty, and the api-rule branch ignores the returned response from createAPIRule entirely.
src/Migration/Transfer.php	Adds GROUP_DOMAINS constant, GROUP_DOMAINS_RESOURCES array, and the corresponding case in extractServices(); all wired up correctly.
src/Migration/Resource.php	Adds TYPE_RULE constant and registers it in ALL_PUBLIC_RESOURCES; straightforward addition.
src/Migration/Source.php	Adds abstract exportGroupDomains method, getDomainsBatchSize(), and routes the GROUP_DOMAINS case in the export dispatch; clean addition.
tests/Migration/Unit/Adapters/MockSource.php	Adds exportGroupDomains stub in MockSource; follows the exact same pattern as existing group stubs.
src/Migration/Sources/Firebase.php	Stub exportGroupDomains that throws 'Not implemented'; consistent with other unsupported source methods.
src/Migration/Sources/NHost.php	Stub exportGroupDomains that throws 'Not Implemented'; consistent with other unsupported source methods.
src/Migration/Sources/CSV.php	Stub exportGroupDomains that throws 'Not Implemented'; consistent with other unsupported source methods.
src/Migration/Sources/JSON.php	Stub exportGroupDomains that throws 'Not Implemented'; consistent with other unsupported source methods.

_{Reviews (5): Last reviewed commit: "Merge remote-tracking branch 'origin/add..." | Re-trigger Greptile}