docs: replace convention docs with AGENTS.md rules and ADRs - #977

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-dotnet@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

'StatExtractor.UpdateStatisticsModel(Model, IDbConnection, int, bool, DirectLakeExtractionMode, int)' is obsolete: 'This method may produce incomplete results if used on a model with DirectLake partitions and DirectLakeExtractionMode parameter set to anything other than ResidentOnly. Use TomExtractor.GetDaxModel instead.'

Possible null reference argument for parameter 'tableName' in 'string GetWorksheetName(string tableName, int tableIndex)'.

Dereference of a possibly null reference.

Possible null reference argument for parameter 'name' in 'ExportDataTable ExportDataJobExtensions.AddNew(ExportDataJob job, string name)'.

Possible null reference argument for parameter 'name' in 'ExportDataTable ExportDataJobExtensions.AddNew(ExportDataJob job, string name)'.

'StatExtractor.UpdateStatisticsModel(Model, IDbConnection, int, bool, DirectLakeExtractionMode, int)' is obsolete: 'This method may produce incomplete results if used on a model with DirectLake partitions and DirectLakeExtractionMode parameter set to anything other than ResidentOnly. Use TomExtractor.GetDaxModel instead.'

Possible null reference argument for parameter 'tableName' in 'string GetWorksheetName(string tableName, int tableIndex)'.

Dereference of a possibly null reference.

Possible null reference argument for parameter 'name' in 'ExportDataTable ExportDataJobExtensions.AddNew(ExportDataJob job, string name)'.