chore(sonar)!: mark instance-data-free members static (CA1822)

Applied via `dotnet format analyzers --diagnostics CA1822 --severity info`.
12 files touched. The fixer also updated internal callers in tests to use
the type-name form (e.g. `gen.Method(x)` -> `Generator.Method(x)`); build
and full test suite remain green.

BREAKING CHANGE: two public methods become static and therefore can no
longer be invoked through an instance reference by external consumers:
- Strata.SqlTools.Markdown.LinqToSql.QueryBreakdownGenerator.GenerateMethodChainDiagram
- Strata.SqlTools.Markdown.LinqToSql.SqlStatementGenerator.GenerateLinqPipelineDiagram

Both are stateless utility methods on Generator classes — the static form
is the correct shape; the only callers in this repo already used the
type-name form. External code should change `gen.GenerateMethodChainDiagram(...)`
to `QueryBreakdownGenerator.GenerateMethodChainDiagram(...)`.

All other CA1822 hits in this commit are on private/protected members
(no public-surface impact).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Strata.SqlTools.LinqToSql/Validators/QueryValidator.cs

@@ -222,7 +222,7 @@ public class QueryValidator
         }
     }
 
-    private void ValidateWhereClause(LinqQueryBreakdown breakdown)
+    private static void ValidateWhereClause(LinqQueryBreakdown breakdown)
     {
         // No validation needed - WHERE is optional
     }
@@ -242,12 +242,12 @@ public class QueryValidator
         }
     }
 
-    private void ValidateHavingClause(LinqQueryBreakdown breakdown)
+    private static void ValidateHavingClause(LinqQueryBreakdown breakdown)
     {
         // Validation delegated to ValidateGroupByClause
     }
 
-    private void ValidateOrderByClause(LinqQueryBreakdown breakdown)
+    private static void ValidateOrderByClause(LinqQueryBreakdown breakdown)
     {
         // No validation needed - ORDER BY is optional
     }

src/Strata.SqlTools.LinqToSql/Visitors/LinqExpressionVisitor.cs

@@ -323,7 +323,7 @@ public class LinqExpressionVisitor : ExpressionVisitor
         return expression.ToString();
     }
 
-    private string GetFullMemberName(MemberExpression expression)
+    private static string GetFullMemberName(MemberExpression expression)
     {
         var parts = new Stack<string>();
         var current = expression;
@@ -354,7 +354,7 @@ public class LinqExpressionVisitor : ExpressionVisitor
         return string.Join(".", parts);
     }
 
-    private string GetOperator(ExpressionType nodeType)
+    private static string GetOperator(ExpressionType nodeType)
     {
         return nodeType switch
         {

src/Strata.SqlTools.Markdown/Expressions/ExpressionGenerator.cs

@@ -260,7 +260,7 @@ public class ExpressionGenerator : IVisitor<string>
         return sb.ToString();
     }
 
-    private int GenerateMermaidNodes(Expression expression, StringBuilder sb, Dictionary<object, int> nodeMap, ref int nodeCounter)
+    private static int GenerateMermaidNodes(Expression expression, StringBuilder sb, Dictionary<object, int> nodeMap, ref int nodeCounter)
     {
         var currentNode = nodeCounter++;
         nodeMap[expression] = currentNode;

src/Strata.SqlTools.Markdown/Expressions/SimpleExpressionGenerator.cs

@@ -106,7 +106,7 @@ public class SimpleExpressionGenerator
         return sb.ToString();
     }
 
-    private string GetExpressionDescription(Expression expression)
+    private static string GetExpressionDescription(Expression expression)
     {
         var typeName = expression.GetType().Name;
 

src/Strata.SqlTools.Markdown/LinqToSql/QueryBreakdownGenerator.cs

@@ -37,7 +37,7 @@ public class QueryBreakdownGenerator
     /// <param name="queryBreakdown">The LINQ QueryBreakdown to visualize.</param>
     /// <param name="title">Optional title for the diagram.</param>
     /// <returns>A string containing the Mermaid flowchart showing method calls.</returns>
-    public string GenerateMethodChainDiagram(LinqQueryBreakdown queryBreakdown, string? title = null)
+    public static string GenerateMethodChainDiagram(LinqQueryBreakdown queryBreakdown, string? title = null)
     {
         var sb = new System.Text.StringBuilder();
 

src/Strata.SqlTools.Markdown/LinqToSql/SqlStatementGenerator.cs

@@ -58,7 +58,7 @@ public class SqlStatementGenerator
     /// <param name="queryBreakdown">The query breakdown containing query information.</param>
     /// <param name="title">Optional title for the diagram.</param>
     /// <returns>A string containing the Mermaid diagram markdown.</returns>
-    public string GenerateLinqPipelineDiagram(IQueryBreakdown queryBreakdown, string? title = null)
+    public static string GenerateLinqPipelineDiagram(IQueryBreakdown queryBreakdown, string? title = null)
     {
         var sb = new System.Text.StringBuilder();
 

src/Strata.SqlTools.Markdown/SqlServer/QueryBreakdownGenerator.cs

@@ -177,7 +177,7 @@ public class QueryBreakdownGenerator
     /// <summary>
     /// Escapes text for Mermaid diagram labels to prevent syntax errors.
     /// </summary>
-    private string EscapeMermaidText(string text)
+    private static string EscapeMermaidText(string text)
     {
         return text
             .Replace("\"", "&quot;")
@@ -194,7 +194,7 @@ public class QueryBreakdownGenerator
     /// <summary>
     /// Truncates text to a maximum length and adds ellipsis if needed.
     /// </summary>
-    private string TruncateText(string text, int maxLength)
+    private static string TruncateText(string text, int maxLength)
     {
         if (string.IsNullOrWhiteSpace(text) || text.Length <= maxLength)
         {

src/Strata.SqlTools.Markdown/SqlServer/SqlStatementGenerator.cs

@@ -104,7 +104,7 @@ public class SqlStatementGenerator
     /// <summary>
     /// Escapes text for Mermaid diagram labels.
     /// </summary>
-    private string EscapeMermaidText(string text)
+    private static string EscapeMermaidText(string text)
     {
         return text
             .Replace("\"", "&quot;")
@@ -115,7 +115,7 @@ public class SqlStatementGenerator
     /// <summary>
     /// Truncates text to a maximum length.
     /// </summary>
-    private string TruncateText(string text, int maxLength)
+    private static string TruncateText(string text, int maxLength)
     {
         if (string.IsNullOrWhiteSpace(text) || text.Length <= maxLength)
         {
@@ -128,7 +128,7 @@ public class SqlStatementGenerator
     /// <summary>
     /// Cleans table name for use in Mermaid diagrams.
     /// </summary>
-    private string CleanTableName(string tableName)
+    private static string CleanTableName(string tableName)
     {
         return tableName
             .Replace("[", "")