fix(migration): add cleanup step for duplicate push subscriptions before enforcing unique constraint

[0xSysR3ll]

Description

This PR fixes duplicate user_push_subscription entries by removing them before applying the UNIQUE constraint on (endpoint, userId).

• Fixes SQLite duplicate entries (user_push_subscription table) #2265

How Has This Been Tested?

1. Inserted dummy duplicate user_push_subscription entries.
2. Ran the migration.
3. Verified that duplicates were removed and the UNIQUE constraint was applied successfully.

Screenshots / Logs (if applicable)

Checklist:

• I have read and followed the contribution guidelines.
• Disclosed any use of AI (see our policy)
• I have updated the documentation accordingly.
• All new and existing tests passed.
• Successful build pnpm build
• Translation keys pnpm i18n:extract
• Database migration (if required)

[Copilot]

Pull request overview

This PR addresses duplicate entries in the user_push_subscription table by adding a cleanup step before enforcing a unique constraint on the (endpoint, userId) column pair. The migration prevents constraint violation errors when upgrading existing installations that may have accumulated duplicate push subscription records.

Key Changes:

• Added DELETE query to remove duplicate push subscriptions, keeping only the record with the highest ID for each (endpoint, userId) combination
• Applied UNIQUE constraint/index on (endpoint, userId) columns after cleanup
• Implemented the fix consistently for both PostgreSQL and SQLite databases

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
server/migration/postgres/1765233385034-AddUniqueConstraintToPushSubscription.ts	Adds duplicate removal query and applies UNIQUE constraint for PostgreSQL
server/migration/sqlite/1765233385034-AddUniqueConstraintToPushSubscription.ts	Adds duplicate removal query and creates UNIQUE index for SQLite

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.