feat: Phase 1 - Canvas with React Flow

- 8 node types (Model, Solver, DesignVar, Extractor, Objective, Constraint, Algorithm, Surrogate)
- Drag-drop from palette to canvas
- Node configuration panels
- Graph validation with error/warning display
- Intent JSON serialization
- Zustand state management

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

atomizer-dashboard/frontend/src/lib/canvas/schema.ts

@@ -0,0 +1,102 @@
+/**
+ * Canvas Schema - Type definitions for optimization workflow nodes
+ */
+
+export type NodeType =
+  | 'model'
+  | 'solver'
+  | 'designVar'
+  | 'extractor'
+  | 'objective'
+  | 'constraint'
+  | 'algorithm'
+  | 'surrogate';
+
+export interface BaseNodeData {
+  label: string;
+  configured: boolean;
+  errors?: string[];
+}
+
+export interface ModelNodeData extends BaseNodeData {
+  type: 'model';
+  filePath?: string;
+  fileType?: 'prt' | 'fem' | 'sim';
+}
+
+export interface SolverNodeData extends BaseNodeData {
+  type: 'solver';
+  solverType?: 'SOL101' | 'SOL103' | 'SOL105' | 'SOL106' | 'SOL111' | 'SOL112';
+}
+
+export interface DesignVarNodeData extends BaseNodeData {
+  type: 'designVar';
+  expressionName?: string;
+  minValue?: number;
+  maxValue?: number;
+  unit?: string;
+}
+
+export interface ExtractorNodeData extends BaseNodeData {
+  type: 'extractor';
+  extractorId?: string;
+  extractorName?: string;
+  config?: Record<string, unknown>;
+}
+
+export interface ObjectiveNodeData extends BaseNodeData {
+  type: 'objective';
+  name?: string;
+  direction?: 'minimize' | 'maximize';
+  weight?: number;
+}
+
+export interface ConstraintNodeData extends BaseNodeData {
+  type: 'constraint';
+  name?: string;
+  operator?: '<' | '<=' | '>' | '>=' | '==';
+  value?: number;
+}
+
+export interface AlgorithmNodeData extends BaseNodeData {
+  type: 'algorithm';
+  method?: 'TPE' | 'CMA-ES' | 'NSGA-II' | 'GP-BO' | 'RandomSearch';
+  maxTrials?: number;
+}
+
+export interface SurrogateNodeData extends BaseNodeData {
+  type: 'surrogate';
+  enabled?: boolean;
+  modelType?: 'MLP' | 'GNN' | 'Ensemble';
+  minTrials?: number;
+}
+
+export type CanvasNodeData =
+  | ModelNodeData
+  | SolverNodeData
+  | DesignVarNodeData
+  | ExtractorNodeData
+  | ObjectiveNodeData
+  | ConstraintNodeData
+  | AlgorithmNodeData
+  | SurrogateNodeData;
+
+export interface CanvasEdge {
+  id: string;
+  source: string;
+  target: string;
+  sourceHandle?: string;
+  targetHandle?: string;
+}
+
+// Valid connections
+export const VALID_CONNECTIONS: Record<NodeType, NodeType[]> = {
+  model: ['solver', 'designVar'],
+  solver: ['extractor'],
+  designVar: ['model'],
+  extractor: ['objective', 'constraint'],
+  objective: ['algorithm'],
+  constraint: ['algorithm'],
+  algorithm: ['surrogate'],
+  surrogate: [],
+};