fix: support mysql-compatible databases that only support constant values in set statements

[ellie]

Resolves #357

Tasks

• Regenerated TS-RS bindings (if any ts(export) structs have changed)
• Updated the documentation in docs/ (if any application behavior has changed)
• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle

[greptile-apps]

Greptile Summary

Added opt-in support for MySQL-compatible databases (StarRocks, Doris) that don't support dynamic SET statements. Users can now enable "Skip SQL mode initialization" in MySQL block settings to disable pipes_as_concat and no_engine_substitution sqlx options.

• Backend adds skip_sql_mode_init boolean flag to MySQL block configuration
• Frontend adds settings modal with toggle switch for the new option
• Changes properly propagated through TypeScript models and React components
• Maintains backwards compatibility with default value of false

Important Files Changed

Filename	Overview
crates/atuin-desktop-runtime/src/blocks/mysql.rs	Added skipSqlModeInit flag to disable dynamic SET statements for StarRocks/Doris compatibility
src/components/runbooks/editor/blocks/MySQL/MySQL.tsx	Added UI toggle for skipSqlModeInit with settings modal
src/lib/blocks/common/SQL.tsx	Added generic settings modal infrastructure for SQL blocks
src/lib/workflow/blocks/mysql.ts	Added skipSqlModeInit property to MySqlBlock model with proper serialization