refactor(connectors): share MySQL/MariaDB schema introspection

[tianzhou]

Summary

Follow-up to #467. The MySQL and MariaDB connectors carried near-identical copies of every INFORMATION_SCHEMA / SHOW CREATE method (getSchemas, getTables, getViews, tableExists, getTableIndexes, getTableSchema, getTableComment, getStoredProcedures, getStoredProcedureDetail, getDefaultSchema), differing only in the driver's result shape. Fixes could land in one and not the other.

• New src/connectors/mysql-family-introspection.ts holds those methods as functions over a row-array query adapter, following the convention mysql-family-health-check.ts already uses.
• Each connector keeps a small private requireQuery() that owns the "not connected" check and unwraps its driver's result shape (mysql2 resolves to [rows, fields]; mariadb to rows). The health check now goes through the same adapter.
• Driver-specific code (DSN parsing, pooling, timeouts, executeSQL) stays in each connector's index.ts.

No behaviour change: the SQL, parameters, error messages and logging are unchanged, and the adapters call pool.query with the same arity as before (second argument omitted when there are no parameters).

File	Before	After
mysql/index.ts	807	423
mariadb/index.ts	747	363
mysql-family-introspection.ts	new	419

Test plan

• pnpm run build succeeds
• pnpm test:unit passes (1201 tests)
• tsc --noEmit clean in src/connectors/
• CI integration suites for MySQL and MariaDB, which need Docker and could not run locally

🤖 Generated with Claude Code

https://claude.ai/code/session_01T79tgGfqWNqUeTwhRc65MJ

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Generated by Claude Code

[Copilot]

🟢 Approval recommended

The extraction preserves SQL, parameter handling, errors, and driver-specific result unwrapping without identified regressions.

0 open findings

What changed in this PR

Centralizes MySQL and MariaDB schema introspection while preserving connector-specific driver behavior.

Changes:

• Extracts shared introspection functions.
• Adds driver-specific row adapters.
• Reuses adapters for health checks.

File	Description
src/​connectors/​mysql/​index.ts	Delegates introspection through the mysql2 adapter.
src/​connectors/​mariadb/​index.ts	Delegates introspection through the MariaDB adapter.
src/​connectors/​mysql-family-introspection.ts	Provides shared MySQL-family introspection logic.

🧠 Review effort: Balanced

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