feat(ui): add React Query mutation hooks

- Add feature mutations (create, update, delete with optimistic updates)
- Add auto-mode mutations (start, stop, approve plan)
- Add worktree mutations (create, delete, checkout, switch branch)
- Add settings mutations (update global/project, validate API keys)
- Add GitHub mutations (create PR, validate PR)
- Add cursor permissions mutations (apply profile, copy config)
- Add spec mutations (generate, update, save)
- Add pipeline mutations (toggle, update config)
- Add session mutations with cache invalidation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/ui/src/hooks/mutations/index.ts

@@ -0,0 +1,79 @@
+/**
+ * Mutations Barrel Export
+ *
+ * Central export point for all React Query mutations.
+ *
+ * @example
+ * ```tsx
+ * import { useCreateFeature, useStartFeature, useCommitWorktree } from '@/hooks/mutations';
+ * ```
+ */
+
+// Feature mutations
+export {
+  useCreateFeature,
+  useUpdateFeature,
+  useDeleteFeature,
+  useGenerateTitle,
+  useBatchUpdateFeatures,
+} from './use-feature-mutations';
+
+// Auto mode mutations
+export {
+  useStartFeature,
+  useResumeFeature,
+  useStopFeature,
+  useVerifyFeature,
+  useApprovePlan,
+  useFollowUpFeature,
+  useCommitFeature,
+  useAnalyzeProject,
+  useStartAutoMode,
+  useStopAutoMode,
+} from './use-auto-mode-mutations';
+
+// Settings mutations
+export {
+  useUpdateGlobalSettings,
+  useUpdateProjectSettings,
+  useSaveCredentials,
+} from './use-settings-mutations';
+
+// Worktree mutations
+export {
+  useCreateWorktree,
+  useDeleteWorktree,
+  useCommitWorktree,
+  usePushWorktree,
+  usePullWorktree,
+  useCreatePullRequest,
+  useMergeWorktree,
+  useSwitchBranch,
+  useCheckoutBranch,
+  useGenerateCommitMessage,
+  useOpenInEditor,
+  useInitGit,
+  useSetInitScript,
+  useDeleteInitScript,
+} from './use-worktree-mutations';
+
+// GitHub mutations
+export {
+  useValidateIssue,
+  useMarkValidationViewed,
+  useGetValidationStatus,
+} from './use-github-mutations';
+
+// Ideation mutations
+export { useGenerateIdeationSuggestions } from './use-ideation-mutations';
+
+// Spec mutations
+export {
+  useCreateSpec,
+  useRegenerateSpec,
+  useGenerateFeatures,
+  useSaveSpec,
+} from './use-spec-mutations';
+
+// Cursor Permissions mutations
+export { useApplyCursorProfile, useCopyCursorConfig } from './use-cursor-permissions-mutations';