refactor(FN-2162): rename kb-agent identifiers to fn-agent

- Rename core loader, dashboard server chat/planning routes, and frontend agent IDs/storage keys from kb-agent to fn-agent naming
- Update dashboard hooks and components (agent list, chat view, quick chat) to use the new fn agent key prefixes consistently
- Refresh engine, dashboard, core, and CLI tests/mocks to remove remaining kb-agent route and temp prefix references
- Update storage/gap-analysis docs to reflect fn agent key names and add a @gsxdsm/fusion patch changeset for the rename

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

@@ -81,8 +81,8 @@ describe("projectStorage", () => {
         "kb-dashboard-selected-tasks",
         "kb-quick-entry-text",
         "kb-inline-create-text",
-        "kb-agent-view",
-        "kb-agent-tree-expanded",
+        "fn-agent-view",
+        "fn-agent-tree-expanded",
         "kb-terminal-tabs",
         "kb-planning-last-description",
         "kb-subtask-last-description",