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 support: a new Rule resource, GROUP_DOMAINS group, source export (Appwrite SDK's Proxy service with cursor pagination), and destination import dispatching to the four createAPIRule / createFunctionRule / createSiteRule / createRedirectRule endpoints. Auto-generated .appwrite.network rules are skipped, and 409 conflicts surface as warnings rather than aborting the migration.

• New Rule resource & GROUP_DOMAINS group — Resources/Domains/Rule.php models all proxy-rule fields; Transfer::GROUP_DOMAINS_RESOURCES and the corresponding constants are wired through Source, Transfer, and both Appwrite adapters.
• Source export — exportRules() paginates via cursor, maps SDK response objects to Rule instances, and wraps errors with typed Exception objects.
• Destination import — createRule() skips auto-generated rules, dispatches on type + deploymentResourceType, and surfaces domain-ownership conflicts (409) as STATUS_WARNING; all other sources stub exportGroupDomains() as not implemented.

Confidence Score: 4/5

Mostly safe, but Transfer.php still has a gap where GROUP_SETTINGS cannot be expanded via extractServices(), which will throw for any caller using that group.

The domains migration logic itself is well-structured, but GROUP_SETTINGS remains absent from extractServices() even though this PR correctly added GROUP_DOMAINS. Since GROUP_SETTINGS_RESOURCES is now fully populated, any caller passing GROUP_SETTINGS to extractServices() hits the default throw branch — a real defect on the changed path in Transfer.php.

src/Migration/Transfer.php — the extractServices() match expression is missing GROUP_SETTINGS.

Important Files Changed

Filename	Overview
src/Migration/Transfer.php	Adds GROUP_DOMAINS constant and GROUP_DOMAINS_RESOURCES array, and wires GROUP_DOMAINS into extractServices() — but GROUP_SETTINGS is still absent from extractServices(), causing a thrown exception for any caller using that group.
src/Migration/Destinations/Appwrite.php	Adds importDomainsResource() and createRule() dispatching to four proxy-rule endpoints; redirect rule case has a silent fallback to FUNCTION type when deploymentResourceType is empty.
src/Migration/Sources/Appwrite.php	Adds exportGroupDomains() and exportRules() with cursor-based pagination; minor edge case where callback is invoked with an empty array when rule count is an exact multiple of batchSize.
src/Migration/Resources/Domains/Rule.php	New Rule resource class with full constructor, fromArray(), jsonSerialize(), getName(), and getGroup() — looks correct and complete.
src/Migration/Source.php	Adds getDomainsBatchSize(), GROUP_DOMAINS mapping in the resource loop, and the abstract exportGroupDomains() method — straightforward, consistent with existing patterns.
src/Migration/Resource.php	Adds TYPE_RULE constant and includes it in the all-resources list — minimal, correct change.
src/Migration/Sources/CSV.php	Stubbed exportGroupDomains() throwing 'Not Implemented' — satisfies the new abstract method contract.
src/Migration/Sources/Firebase.php	Stubbed exportGroupDomains() throwing 'Not implemented' — satisfies the new abstract method contract.
src/Migration/Sources/JSON.php	Stubbed exportGroupDomains() throwing 'Not Implemented' — satisfies the new abstract method contract.
src/Migration/Sources/NHost.php	Stubbed exportGroupDomains() throwing 'Not Implemented' — satisfies the new abstract method contract.
tests/Migration/Unit/Adapters/MockSource.php	Implements exportGroupDomains() in MockSource consistent with the existing mock pattern for other groups.

_{Reviews (2): Last reviewed commit: "Merge remote-tracking branch 'origin/add..." | Re-trigger Greptile}

[greptile-apps]

GROUP_SETTINGS still missing from extractServices()

GROUP_DOMAINS was added to the extractServices() match expression in this PR, but GROUP_SETTINGS is still absent. Any caller that passes Transfer::GROUP_SETTINGS to extractServices() will hit the default branch and throw \Exception('No service group found'), making the entire settings group unexpandable through this method even though GROUP_SETTINGS_RESOURCES is fully populated.