test: add AISnapshotStore integration tests

Add integration tests covering snapshot data consistency: content-
addressable dedup, snapshot building/back-fill, multi-response
restore, file creation/deletion flows, and reset behavior. Expose
AISnapshotStore via brackets.test for test window access.

Author: abose

src/brackets.js

@@ -296,6 +296,7 @@ define(function (require, exports, module) {
             SidebarTabs: require("view/SidebarTabs"),
             SidebarView: require("project/SidebarView"),
             WorkingSetView: require("project/WorkingSetView"),
+            AISnapshotStore: require("core-ai/AISnapshotStore"),
             doneLoading: false
         };
 

src/core-ai/AISnapshotStore.js

@@ -36,7 +36,7 @@ define(function (require, exports, module) {
 
     // --- Constants ---
     const HEARTBEAT_INTERVAL_MS = 60 * 1000;
-    const STALE_THRESHOLD_MS = 20 * 60 * 1000;
+    const STALE_THRESHOLD_MS = 10 * 60 * 1000;
 
     // --- Disk store state ---
     let _instanceDir;           // "<appSupportDir>/instanceData/<instanceId>/"

test/UnitTestSuite.js

@@ -62,6 +62,7 @@ define(function (require, exports, module) {
     require("spec/KeybindingManager-integ-test");
     require("spec/LanguageManager-test");
     require("spec/LanguageManager-integ-test");
+    require("spec/ai-snapshot-test");
     require("spec/LowLevelFileIO-test");
     require("spec/Metrics-test");
     require("spec/MultiRangeInlineEditor-test");