refactor: replace a couple of unintended/deprecated usages

- fleet.multiplatform.shims.ConcurrentHashSet was unintended
- PrefixMatcher.ALWAYS_TRUE is deprecated in 2026.1

Author: lppedd

src/main/kotlin/com/github/lppedd/cc/completion/providers/NoScopeCompletionProvider.kt

@@ -5,7 +5,7 @@ import com.github.lppedd.cc.completion.LookupElementKey
 import com.github.lppedd.cc.completion.resultset.ResultSet
 import com.github.lppedd.cc.lookupElement.CommitNoScopeLookupElement
 import com.github.lppedd.cc.psiElement.NoScopeCommitPsiElement
-import com.intellij.codeInsight.completion.PrefixMatcher
+import com.intellij.codeInsight.completion.PlainPrefixMatcher
 import com.intellij.openapi.project.Project
 
 /**
@@ -23,6 +23,6 @@ internal class NoScopeCompletionProvider(
   override fun complete(resultSet: ResultSet) {
     val element = CommitNoScopeLookupElement(NoScopeCommitPsiElement(project))
     element.putUserData(LookupElementKey.Index, Int.MAX_VALUE)
-    resultSet.withPrefixMatcher(PrefixMatcher.ALWAYS_TRUE).addElement(element)
+    resultSet.withPrefixMatcher(PlainPrefixMatcher.ALWAYS_TRUE).addElement(element)
   }
 }

src/main/kotlin/com/github/lppedd/cc/vcs/InternalVcsService.kt

@@ -14,8 +14,8 @@ import com.intellij.vcs.log.graph.PermanentGraph
 import com.intellij.vcs.log.impl.VcsLogManager
 import com.intellij.vcs.log.impl.VcsProjectLog
 import com.intellij.vcs.log.visible.filters.VcsLogFilterObject
-import fleet.multiplatform.shims.ConcurrentHashSet
 import java.util.*
+import java.util.concurrent.ConcurrentHashMap
 import kotlin.coroutines.cancellation.CancellationException
 import kotlin.io.path.notExists
 
@@ -32,7 +32,7 @@ internal class InternalVcsService(private val project: Project) : VcsService {
     private val logger = logger<InternalVcsService>()
   }
 
-  private val refreshListeners = ConcurrentHashSet<VcsService.VcsListener>()
+  private val refreshListeners = ConcurrentHashMap.newKeySet<VcsService.VcsListener>()
   private val vcsLogRefresher = MyVcsLogRefresher()
   private val subscribedVcsLogProviders = Collections.newSetFromMap<VcsLogProvider>(IdentityHashMap())