fix: address Copilot PR #7 review feedback

- release.yml: add concurrency group to prevent race conditions when
  multiple pushes to master happen close together; cancel-in-progress
  is false so a running release is never aborted mid-way
- release.yml: add explicit 'Fail if this version was already released'
  step after tag_check so a duplicate-version push to master fails
  loudly with ::error:: rather than silently succeeding with no publish
- CollectionDefinitions.cs: fix XML doc cref targets — qualify
  DisableParallelization as Xunit.CollectionDefinitionAttribute.DisableParallelization
  and remove the space in ConcurrentDictionary{TKey,TValue} to avoid
  CS1574 warnings when doc generation is enabled

Author: gragra33

.github/workflows/release.yml

@@ -5,6 +5,10 @@ on:
         branches:
             - master
 
+concurrency:
+    group: ${{ github.workflow }}-${{ github.ref }}
+    cancel-in-progress: false
+
 jobs:
     release:
         name: Build, Test & Publish to NuGet
@@ -53,6 +57,12 @@ jobs:
                     echo "exists=false" >> $GITHUB_OUTPUT
                   fi
 
+            - name: Fail if this version was already released
+              if: steps.tag_check.outputs.exists == 'true'
+              run: |
+                  echo "::error::Release tag ${{ steps.version.outputs.tag }} already exists. Bump the project version before pushing to master."
+                  exit 1
+
             - name: Pack NuGet package
               if: steps.tag_check.outputs.exists == 'false'
               run: |

tests/Blazing.Json.Queryable.Tests/CollectionDefinitions.cs

@@ -7,12 +7,12 @@ namespace Blazing.Json.Queryable.Tests;
 /// </summary>
 /// <remarks>
 /// <para>
-/// <see cref="DisableParallelization"/> is set to <see langword="true"/> so that when any
+/// <see cref="Xunit.CollectionDefinitionAttribute.DisableParallelization"/> is set to <see langword="true"/> so that when any
 /// test in this collection executes, no other test collection runs concurrently.
 /// </para>
 /// <para>
 /// This is required because <see cref="Blazing.Json.Queryable.Implementations.SpanPropertyAccessor"/>
-/// uses a process-wide static <see cref="System.Collections.Concurrent.ConcurrentDictionary{TKey, TValue}"/>
+/// uses a process-wide static <see cref="System.Collections.Concurrent.ConcurrentDictionary{TKey,TValue}"/>
 /// cache. Tests in this collection call <c>ClearCache()</c> and assert on <c>CacheCount</c> —
 /// assertions that are only valid when no other test is concurrently populating the cache.
 /// </para>