fix(FN-1817): enrich session list with lastMessagePreview and restore active session on remount

- Add lastMessagePreview field to ChatSession to show message previews in session list
- Restore active session state on component remount via stored lastSessionId
- Add chat routes for session management (create, list, read, update/delete)
- Add tests for useChat hook, chat store, and chat routes
- Remove unused serveCommand assignment in serve.ts command

packages/dashboard/app/utils/projectStorage.test.ts

@@ -88,9 +88,10 @@ describe("projectStorage", () => {
         "kb-subtask-last-description",
         "kb-mission-last-goal",
         "kb-usage-view-mode",
+        "kb-chat-active-session",
       ]),
     );
-    expect(PROJECT_STORAGE_KEYS).toHaveLength(14);
+    expect(PROJECT_STORAGE_KEYS).toHaveLength(15);
   });
 
   it("has no overlap between global and project-scoped keys", () => {

packages/dashboard/app/utils/projectStorage.ts

@@ -21,6 +21,7 @@ export const PROJECT_STORAGE_KEYS: string[] = [
   "kb-subtask-last-description",
   "kb-mission-last-goal",
   "kb-usage-view-mode",
+  "kb-chat-active-session",
 ];
 
 export function scopedKey(baseKey: string, projectId?: string): string {