feat(KB-332): rename task prefix from KB to FN and branches from kb/ to fusion/

- Change default task prefix from KB to FN across all packages

- Rename branch naming pattern from kb/{id} to fusion/{id}

- Update all test assertions and fixtures to use new prefixes

- Add changeset for the breaking change

- Resolve merge conflicts in TaskCard.test.tsx touch gesture tests

.changeset/rename-task-prefix-and-branches.md

@@ -0,0 +1,8 @@
+---
+"@fusion/core": minor
+"@fusion/dashboard": minor
+"@fusion/engine": minor
+"@gsxdsm/fusion": minor
+---
+
+Rename default task ID prefix from KB- to FN- and branch naming from kb/ to fusion/