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 adds custom-domain proxy-rule migration between Appwrite projects. It introduces a Rule resource, a GROUP_DOMAINS group, full cursor-paginated export from the source's Proxy service, and dispatch to the four createAPIRule / createFunctionRule / createSiteRule / createRedirectRule endpoints on the destination, with auto-generated rules skipped and 409 conflicts surfaced as warnings.

• Rule resource & group wiring (Resource.php, Transfer.php, Source.php) — clean and consistent with the existing group pattern; GROUP_DOMAINS is correctly added to extractServices().
• Source export (Sources/Appwrite.php) — cursor pagination mirrors other exporters; reportDomains counts all rules including auto-generated ones, so the pre-migration estimate will be higher than the rules actually imported.
• Destination import (Destinations/Appwrite.php) — rule-type dispatch is clear; the redirect branch's fallback of FUNCTIONMODEL when deploymentResourceType is empty was flagged in a previous review pass.

Confidence Score: 5/5

Safe to merge; the only new finding is a cosmetic count mismatch in the pre-migration report that does not affect migration correctness.

The core migration path — export, transfer, and import of proxy rules — is functionally correct. The one new finding (inflated rule count in reportDomains) affects only the progress estimate shown to the user, not the actual rules created on the destination.

src/Migration/Sources/Appwrite.php (reportDomains) and src/Migration/Destinations/Appwrite.php (createRule redirect branch) warrant a second look before the E2E test run.

Important Files Changed

Filename	Overview
src/Migration/Resources/Domains/Rule.php	New value-object for proxy rules; well-structured with correct defaults and JSON serialisation.
src/Migration/Sources/Appwrite.php	Adds exportGroupDomains/exportRules with cursor pagination; reportDomains counts all rules including auto-generated ones that will be skipped, inflating the pre-migration estimate.
src/Migration/Destinations/Appwrite.php	Adds importDomainsResource/createRule; redirect rule resourceType/resourceId handling for empty deploymentResourceType already flagged separately.
src/Migration/Transfer.php	Adds GROUP_DOMAINS constant, GROUP_DOMAINS_RESOURCES, and extractServices() arm correctly.
src/Migration/Source.php	Adds abstract exportGroupDomains and wires it into the export dispatch; consistent with existing pattern.
src/Migration/Resource.php	Adds TYPE_RULE constant and registers it in the all-types list; clean.
tests/Migration/Unit/Adapters/MockSource.php	Adds exportGroupDomains and TYPE_RULE to supported resources; correctly mirrors the pattern used by other groups.
tests/Migration/Unit/Adapters/MockDestination.php	Adds TYPE_RULE to supported types list; correct.

_{Reviews (7): Last reviewed commit: "Merge branch 'add-smtp-migration' into a..." | Re-trigger Greptile}