[datlechin]

Summary

• New SQLExecutableCommentReadings: the texts a MySQL, MariaDB or TiDB server may run from a statement, one per server family and version threshold. A skipped or plain comment is blanked, a run comment is unwrapped.
• Modelled per server: /*!NNNNN skipped above the server's version past one nested /* */, MariaDB's /*!50700../*!99999 band, 5 or 6 version digits, /*M! plain on MySQL, /*T! run on TiDB, /*m! plain everywhere, OceanBase's flat retry.
• Every gate reads all of them through SQLLexicalReadings.lexings(of:) and keeps the worst: Safe Mode levels, MCP, AI chat, AppleScript, the CLI, dashboard tiles, iOS, catalog refresh, row write refusal.
• A text with more than 32 distinct versions is read as its worst case.
• When no comment can move a statement boundary, each statement is read under its own comments only, so a mysqldump costs about 4 scans instead of one per version.
• The lexer takes only /*! and /*M! as executable, and lexes a run body as code: nested comments, # and -- , no second level. The PluginKit lexer matches.
• File markers match across comments and spaces (INTO/**/OUTFILE, LOAD_FILE (), and ALTER TABLE ... TRUNCATE PARTITION is destructive.
• MySQLSessionFootprint reads the statement behind a version comment a server may skip.
• SQL import reads a run conditional comment's body as code, and reads mysqldump's DELIMITER ;;.
• Probe apple/scripts/probes/check-mysql-executable-comments.sh: passes on MySQL 8.0.46 and 8.4.11, MariaDB 11.4.13, TiDB 8.5.1.

Test plan

• SQLExecutableCommentReadingsTests: each measured text drops the table under exactly the servers that dropped it, and every server's statements are among the texts the gates read.
• ExecutionGateExecutableCommentTests: each executable comment form hiding a DROP is refused in Read-Only and confirmed as destructive at every other Safe Mode level, on MySQL and MariaDB.
• New cases in QueryClassifierExecutableCommentTests, ExternalStatementGateExecutableCommentTests, DashboardTilePolicyTests, SQLWriteClassifierTests, CatalogChangeClassifierTests, SQLFileParserTests, SQLStatementSplittingTests, SQLLexicalFeatureMappingTests, MySQLSessionFootprintTests.
• Unit plan and the TableProCore suites pass.

Fixes #3784