Fix: Activate carrier path for scalar Set<TValue> chains

SyntacticClauseTranslator was creating SetClauseInfo with an empty
parameters list, so BuildChainParameters found no parameter to create
a carrier P{n} field from. Add a synthetic ParameterInfo for the value
parameter using the column's FullClrType, enabling carrier optimization
for all scalar Set chains across all dialects.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: DJGosnell

src/Quarry.Generator/Translation/SyntacticClauseTranslator.cs

@@ -51,6 +51,22 @@ public ClauseInfo Translate(PendingClauseInfo pending)
                 return new OrderByClauseInfo(sql, pending.IsDescending, _parameters, keyTypeName);
             }
 
+            if (pending.Kind == ClauseKind.Set)
+            {
+                // Set clause: the SQL is the quoted column name, parameter at index 0 is the value.
+                // Create a synthetic ParameterInfo for the value (second argument to Set<TValue>).
+                // On the semantic path this comes from GetTypeInfo(valueArg); here we use the
+                // column's CLR type since Set(u => u.Prop, value) requires matching types.
+                var valueTypeName = ResolveKeyTypeFromExpression(pending.Expression);
+                var valueClrType = valueTypeName ?? "object";
+                var paramIndex = _parameterIndex;
+                var syntheticParams = new List<ParameterInfo>(_parameters)
+                {
+                    new ParameterInfo(paramIndex, $"@p{paramIndex}", valueClrType, "value")
+                };
+                return new SetClauseInfo(sql, paramIndex, syntheticParams, valueTypeName: valueTypeName);
+            }
+
             return ClauseInfo.Success(pending.Kind, sql, _parameters);
         }
         catch (Exception ex)

src/Quarry.Tests/Generation/CarrierGenerationTests.cs

@@ -593,8 +593,8 @@ public static async Task Test(TestDbContext db, int userId, string newName)
         Assert.That(interceptorsTree, Is.Not.Null, "Should generate interceptors file");
 
         var code = interceptorsTree!.GetText().ToString();
-        // Update chains with Set clauses may not be carrier-eligible (Set uses open generic),
-        // but the chain should still be analyzed and produce interceptors
+        // Update chains with scalar Set clauses are carrier-eligible when ValueTypeName is resolved
         Assert.That(code, Does.Contain("UPDATE"));
+        Assert.That(code, Does.Contain("Carrier-Optimized PrebuiltDispatch"));
     }
 }