Quote phonetic_question RANK so MySQL 8 write-back inserts succeed - #22

Summary

UAT smoke of #21 (2.1.1-245 / 497c987) returned HTTP 408 with an empty body for enriched misses such as serendipity and petrichor.

Hibernate sent insert into phonetic_question (..., RANK, WORD) values (...). MySQL 8.0.32 treats bare RANK as a reserved word, so the insert failed with SQLSyntaxErrorException near 'RANK,WORD) values ('. That exception is an InvalidDataAccessResourceUsageException, which insertIfAbsent does not catch, and VocabPracticeController maps it to 408. No rank-0 rows were written. Bank hits such as apple still worked because selected columns are table-qualified.

@Column(name = "\"RANK\"") makes the MySQL dialect emit `RANK` on insert and update. Other columns stay unquoted. No schema job.

Write-back rules are unchanged: true miss only, both IPA and pronunciation URL, rank 0, picture hide left as-is.

Tests

./gradlew test is green.

• PhoneticQuestionMysqlRankSqlTest renders insert and update with the MySQL dialect and fails if RANK is unquoted. H2 accepted the old SQL, which is why the original suite missed this.
• PhoneticQuestionWriteBackTest and PhoneticQuestionServiceTest still cover the insert path.

Not deployed.