feat: soft delete user

[capJavert]

• preserve deleted user ids
• preserve deleted user transactions under ghost
• check for deleted user ids collision on user creation
• add new handler for deleted user collision in safeInsertUser
• also apply delete user logic to zombie user cron

[capJavert]

Instead of RULE create trigger, because RULE was blocking usage of RETURNING in zombie cron.

[Copilot]

Pull Request Overview

This PR implements soft deletion for users by preserving deleted user IDs, checking for collisions during user creation, and handling zombie user cleanup. Key changes include:

• Adding a new telemetry metric counter for deleted user collisions.
• Creating migrations for a DeletedUser table and a trigger to prevent deletion of special users.
• Updating user logic and error handling to support soft deletion and collision detection.

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/telemetry/metrics.ts	Adds metric counter for tracking deleted user collisions.
src/migration/1744972478032-SpecialUserDeleteTrigger.ts	Creates trigger to prevent deletion of special users; includes a potential condition inconsistency and naming typo.
src/migration/1744965354822-DeletedUser.ts	Creates the DeletedUser table for storing soft deleted user records.
src/errors.ts	Adds a new DeletedUserCollisionError and updates error enums.
src/entity/user/utils.ts	Enhances safeInsertUser logic to check for deleted users and handle collisions.
src/entity/user/DeletedUser.ts	Defines the DeletedUser entity for soft delete implementation.
src/cron/cleanZombieUsers.ts	Updates zombie user cleanup to insert records into DeletedUser.
src/common/user.ts	Modifies deleteUser to insert a DeletedUser record after deletion.
tests/private.ts	Adds tests to verify handling of deleted user collisions during user creation.
tests/cron/cleanZombieUsers.ts	Adds tests ensuring deleted user records are created during zombie cleanup.

Comments suppressed due to low confidence (1)

src/migration/1744972478032-SpecialUserDeleteTrigger.ts:10

• [nitpick] The rule name 'prototect_ghostuser_deletion' may be a typo; consider renaming it to 'protect_ghostuser_deletion' for clarity.

`DROP RULE prototect_ghostuser_deletion on "user";`

[omBratteng]

What happens in the user_transaction table? Does the rows get deleted?

[capJavert]

yes, as other user content, njord keeps the log though, although @idoshamun wdyt, should we move user_transaction items to ghost user instead of cascading when user is deleted?

[omBratteng]

I think we should update it to ghost user, so the receiver still can see awards they've been given.

[capJavert]

@omBratteng yeah I agree, see 9402bb6

[Copilot]

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[capJavert]

@idoshamun ready for review again 🙏