fix(mcp): relax column name regex, improve generate_chart validation errors and examples#39866

aminghadersohi wants to merge 4 commits intoapache:masterapache/superset:masterfrom

aminghadersohi:amin/sc-105412-fix-generate-chart-schema-rigidityaminghadersohi/superset:amin/sc-105412-fix-generate-chart-schema-rigidityCopy head branch name to clipboard