refactor(dedup): remove redundant local TruncateText forwarders

`QueryBreakdownGenerator`, `SqlStatementGenerator`, and
`ExpressionGenerator` each had a 1-line `private static string
TruncateText(...)` forwarder to `Internal.MarkdownTextHelpers.TruncateText`.
The forwarders existed only to keep existing call sites short
(`TruncateText(x, 50)` instead of the fully-qualified form).

Each file now imports `using static MarkdownTextHelpers;` once at the
top, so call sites continue to read identically and the local
forwarders are deleted. Removes the structural duplication Sonar was
flagging (two private static helpers — `EscapeMermaidText` + the
TruncateText forwarder — appearing in both `QueryBreakdownGenerator`
and `SqlStatementGenerator` with the same shape).

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

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

@@ -10,6 +10,7 @@ using Strata.SqlTools.SqlBreakdown.Expressions.Functions.Aggregate;
 using Strata.SqlTools.SqlBreakdown.Expressions.Functions.Conditional;
 using Strata.SqlTools.SqlBreakdown.Expressions.Literals;
 using Strata.SqlTools.SqlBreakdown.Interfaces.Core;
+using static Strata.SqlTools.Markdown.Internal.MarkdownTextHelpers;
 
 namespace Strata.SqlTools.Markdown.Expressions;
 
@@ -360,8 +361,6 @@ public class ExpressionGenerator : IVisitor<string>
             .Replace("]", "&#93;");
     }
 
-    private static string TruncateText(string text, int maxLength)
-        => Internal.MarkdownTextHelpers.TruncateText(text, maxLength);
 
     #region IVisitor Implementation
 

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

@@ -1,6 +1,7 @@
 using System.Text;
 using Strata.SqlTools.Breakdowns.SqlServer;
 using Strata.SqlTools.SqlBreakdown.Interfaces;
+using static Strata.SqlTools.Markdown.Internal.MarkdownTextHelpers;
 
 namespace Strata.SqlTools.Markdown.SqlServer;
 
@@ -191,7 +192,5 @@ public static class QueryBreakdownGenerator
             .Replace(">", ">");
     }
 
-    private static string TruncateText(string text, int maxLength)
-        => Internal.MarkdownTextHelpers.TruncateText(text, maxLength);
 }
 

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

@@ -1,5 +1,6 @@
 using System.Text;
 using Strata.SqlTools.SqlBreakdown.Interfaces;
+using static Strata.SqlTools.Markdown.Internal.MarkdownTextHelpers;
 
 namespace Strata.SqlTools.Markdown.SqlServer;
 
@@ -112,9 +113,6 @@ public static class SqlStatementGenerator
             .Replace("\r", "");
     }
 
-    private static string TruncateText(string text, int maxLength)
-        => Internal.MarkdownTextHelpers.TruncateText(text, maxLength);
-
     /// <summary>
     /// Cleans table name for use in Mermaid diagrams.
     /// </summary>