feat: add mindmap components from jarvis frontend

- Copied mindmap visualization components (ReactFlow-based interactive graph)
- Added MindmapViewer, ReactFlowEditor, MermaidViewer
- Included all node types: Concept, Task, Idea, Project
- Added controls: NodeCreateModal, ExportButton
- Created mindmap route at /mindmap
- Added useGraphData hook for knowledge graph API
- Copied auth-client and api utilities (dependencies)

Note: Requires better-auth packages to be installed for full compilation

apps/web/src/components/mindmap/index.ts

@@ -0,0 +1,36 @@
+/**
+ * Mindmap components for knowledge graph visualization
+ *
+ * Provides interactive and static diagram views of knowledge nodes and their relationships.
+ */
+
+// Main viewer components
+export { MindmapViewer } from './MindmapViewer';
+export { ReactFlowEditor } from './ReactFlowEditor';
+export { MermaidViewer } from './MermaidViewer';
+
+// Node components
+export { BaseNode } from './nodes/BaseNode';
+export { ConceptNode } from './nodes/ConceptNode';
+export { TaskNode } from './nodes/TaskNode';
+export { IdeaNode } from './nodes/IdeaNode';
+export { ProjectNode } from './nodes/ProjectNode';
+
+// Control components
+export { NodeCreateModal } from './controls/NodeCreateModal';
+export { ExportButton } from './controls/ExportButton';
+
+// Hooks and types
+export {
+  useGraphData,
+  type KnowledgeNode,
+  type KnowledgeEdge,
+  type NodeCreateInput,
+  type EdgeCreateInput,
+  type GraphData,
+  type MermaidData,
+  type GraphStatistics,
+} from './hooks/useGraphData';
+
+// Type exports for node data
+export type { BaseNodeData } from './nodes/BaseNode';