feat(extensions): Querya Extension Driver Mutation Standard (db.getTableSchema and db.mutate)

[ZhuchkaTriplesix]

Summary

Extend the Querya Extension Driver Protocol to support data editing and mutation across external extension drivers.

Requirements & Scope

• Extend ExtensionDriverCapabilities: add supportsMutations, supportsBatchMutations capability flags.
• Implement db.getTableSchema JSON-RPC method in ExtensionDriverSession for column types, primary keys, and nullable metadata.
• Implement db.mutate JSON-RPC method in ExtensionDriverSession for batch update, insert, and delete mutations.
• Connect ExtensionTableView to DataGridStagingBuffer and dispatch to db.mutate.
• Document the Querya Extension Mutation Standard in SDK docs.