chore: retire auth after its move to Appwrite

[ChiragAgg5k]

Auth now lives in Appwrite following appwrite/appwrite#13890. Remove packages/auth so this repository stops discovering and publishing it during Split runs. Refresh the local dependency graph and list auth with the packages maintained in Appwrite.

No package here requires utopia-php/auth, so no constraint changes.

Validation: bin/monorepo validate and git diff --check pass.

Appwrite merged #13890 as a merge commit, and its post-merge Split pushed auth: the mirror's tree 840730c exactly matches Appwrite's packages/auth. After merge, confirm this repository's Split no longer includes auth.

Still open: draft #137 (OAuth2 clients, identity validators, Phone calling codes) targets packages/auth and packages/validators here, both now retired; it would need re-opening against packages/ in Appwrite.

Part of appwrite/appwrite#13828.

[walter-o-brien]

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