docs: update documentation for extraction functions migration

- Add ExtractionFunctions.md reference document
- Update database-schema spec with 11 extraction functions
- Update data-access spec to document extraction function approach
- Update search-processing spec with new query builder interface
- Add Database.Tests to Testing.md architecture doc
- Update DataFlow.md with extraction function flow

DOCUMENTATION/Architecture/Database.md

@@ -121,7 +121,7 @@ The scoping tool cache database includes these primary tables:
 
 | Table | Purpose |
 |-------|---------|
-| `Search` | User search requests, status, and results (Excel as VARBINARY) |
+| `Search` | User search requests, status, criteria (JSON), and results (Excel as VARBINARY) |
 | `DataUpdate` | Tracks last sync timestamp per data type |
 | `WorkOrder_Curr` | Current work orders from JDE |
 | `WorkOrder_Hist` | Historical work orders from JDE |
@@ -134,6 +134,38 @@ The scoping tool cache database includes these primary tables:
 | `ProfitCenter` | Profit center reference data |
 | `SchemaVersions` | DbUp tracking table (auto-created) |
 
+## Search Criteria Extraction Functions
+
+The database includes SQL functions that extract filter criteria from the `Search.Criteria` JSON column. These functions enable the query builder to pass only a `SearchId` parameter, with all filter extraction happening in SQL Server.
+
+### Scalar Functions (3)
+
+| Function | Returns | Extracts |
+|----------|---------|----------|
+| `fn_GetSearchMinimumDt` | DATETIME2 | `$.MinimumDt` |
+| `fn_GetSearchMaximumDt` | DATETIME2 | `$.MaximumDt` |
+| `fn_GetSearchExtractMisData` | BIT | `$.ExtractMisData` |
+
+### Table-Valued Functions (8)
+
+| Function | Returns | Extracts |
+|----------|---------|----------|
+| `fn_GetSearchWorkOrders` | WorkOrderNumber | `$.WorkOrderNumbers` array |
+| `fn_GetSearchItemNumbers` | ItemNumber | `$.ItemNumbers` array |
+| `fn_GetSearchProfitCenters` | Code | `$.ProfitCenters` array |
+| `fn_GetSearchWorkCenters` | Code | `$.WorkCenters` array |
+| `fn_GetSearchOperatorIDs` | OperatorID | `$.OperatorIDs` array |
+| `fn_GetSearchComponentLots` | LotNumber, ItemNumber | `$.ComponentLotNumbers` array |
+| `fn_GetSearchPartOperations` | ItemNumber, OperationNumber, MisNumber, MisRevision | `$.PartOperations` array |
+
+### Validation Procedure
+
+| Procedure | Purpose |
+|-----------|---------|
+| `usp_ValidateSearchCriteria` | Validates search exists and has valid JSON criteria |
+
+Error codes: 50001 (not found), 50002 (no criteria), 50003 (invalid JSON)
+
 ## Example Migration Scripts
 
 ### 001_CreateSearchTable.sql