fix(mysql): preserve null auto increment metadata

[HandSonic]

Related issue

N/A - no matching issue was found.

Summary

MySQL INFORMATION_SCHEMA.TABLES.AUTO_INCREMENT is nullable, but the metadata mapper used ResultSet.getLong without wasNull. SQL NULL therefore became 0, and downstream DDL generation could treat a table without an auto-increment counter as AUTO_INCREMENT=0. This change preserves null while retaining real increment values.

Affected surfaces

• Frontend / Web
• Backend / API / Storage
• Database plugin / Driver
• JCEF / Desktop packaging
• CI / Build / Release
• Documentation only

Verification

• Commands and results:
  • Red null case returned 0 instead of null; non-null 42 control passed.
  • Focused null/non-null metadata tests: 2 passed.
  • MySQL module tests after rebase: 702 passed.
  • Plugin reactor package: succeeded.
  • Fork code and CodeQL checks: rerunning for the rebased head.
• Manual verification: N/A - a strict ResultSet proxy models JDBC getLong / immediate wasNull semantics.
• UI evidence: N/A

Risk and compatibility

• Public API or stored data: No API or stored data changes.
• Database or driver compatibility: Corrects nullable MySQL table metadata; non-null values are unchanged.
• Network, privacy, or security: N/A.
• Community / Local / Pro boundary: Shared Community MySQL plugin.
• Backward compatibility: Tables with an actual auto-increment counter retain the same value.

Reviewer map

• Start here: MysqlMetaData.tables AUTO_INCREMENT mapping and MysqlTableMetadataNullTest.
• Failure condition: SQL NULL maps to zero or a real increment value is lost.
• Rollback or disable path: Revert commit 915dc9210d18291b56c907f1e7e7dd36d35ab3db; no migration is required.

Contributor declaration

• I linked the Issue that defines this change.
• I tested the affected behavior and reported the actual results above.
• I did not include credentials, private data, or generated build output.
• I disclosed substantial AI assistance below, or this PR contains no substantial AI-generated code.

AI assistance: OpenAI Codex assisted with diagnosis, implementation, automated tests, verification, and adversarial review.