fix(accounts): avoid team auth snapshot collisions

[tinywind]

Summary

• Store saved Codex auth snapshots by account_id + user_id when the access token exposes a user id
• Fall back to the previous account_id-only identity for tokens without a user id
• Keep the runtime auth.json payload unchanged while routing UI switch/remove actions through the unique storage id
• Update the DB import helper and manual verification notes to use the same storage identity

Why

Multiple users in the same ChatGPT team/workspace can share the same tokens.account_id while having distinct user_id and email claims. Using account_id alone causes reload/import to overwrite the previous user snapshot.

Verification

• git diff --check
• Build/test commands were not run per request

[qodo-code-review]

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[friuns2]

I think there is still a migration bug here.

activeAccountId used to be a unique key. After this change it is not. On first load, resolveActiveStorageId() falls back from the legacy activeAccountId to the first matching account with the same accountId.

That means a team with multiple users sharing one accountId can still silently activate the wrong snapshot after upgrade. The overwrite problem is fixed, but active-account restoration is still ambiguous.

I would not merge this without a deterministic migration story for legacy state.