Fix signup loading after account creation

[raymondjacobson]

Summary

• Fix the signup loading page so it finishes once the current account query reports an indexed, complete account.
• Fix identity-service auth middleware to backfill provisional users through the current SDK shape: audiusSdk.users.getUserAccount(...), with a legacy full.users fallback and a 3s timeout.
• Keep /record_ip from 500ing if a request arrives before identity has a handle.

Root cause

• The signup client writes the handle in the create-user EntityManager metadata and API can later return it from /v1/users/account/:wallet.
• Identity /user only creates the provisional row. The intended modern path is auth middleware backfilling blockchainUserId and handle from getUserAccount.
• Identity now loads @audius/sdk via sdk(...), which exposes users at the top level. The middleware still called audiusSdk.full.users, so the backfill failed and identity rows stayed null.

Testing

• node --check packages/identity-service/src/authMiddleware.js
• node --check packages/identity-service/src/routes/idSignals.js
• git diff --check

Note: the normal package test runner was not available in this local worktree because npm, pnpm, yarn, and corepack are absent.

[changeset-bot]

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Latest commit: 66c0602

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