fix(server/storage): stop consuming auto-increment ids on player saves

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Every save runs INSERT ... ON DUPLICATE KEY UPDATE against players, whose id column is AUTO_INCREMENT. With the default innodb_autoinc_lock_mode (1 on MariaDB, 2 on MySQL 8), InnoDB allocates a new id before it finds the duplicate citizenid, so every save of an existing character burns an id. Since #731 every SetMetadata call saves, so a busy server goes through ids quickly, and once the counter passes the signed INT max the upsert fails with Out of range value for column 'id'. After that no existing character can be saved.

This updates the row by citizenid first and only runs the original upsert when no row matched (a new character, or a concurrent first save). The same columns are written in both paths, and a new character still gets a single row.

Tested on MariaDB 11.4 using the statements from this change: one character saved 6 times kept AUTO_INCREMENT at 2 and the next character got id 2. The old query moved the counter to 6 after 5 saves. Lint is clean.

Fixes #762