feat(appserver): add thread mapping store abstraction

Author: loong10k

src/main/java/io/github/easy4j/codex/appserver/ThreadMappingStore.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2018-present, easy-4-java (https://github.com/easy-4-java).
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ */
+package io.github.easy4j.codex.appserver;
+
+/**
+ * Storage abstraction for logical session-key to Codex thread-id mappings.
+ */
+public interface ThreadMappingStore {
+
+    String get(String sessionKey);
+
+    void put(String sessionKey, String threadId);
+
+    void remove(String sessionKey);
+}