feat: initial CodeBoard monorepo scaffold

Turborepo monorepo with npm workspaces:
- apps/web: Next.js 14 frontend with Tailwind v4, SSE progress, doc viewer
- apps/worker: BullMQ job processor (clone → parse → LLM generate)
- packages/shared: TypeScript types
- packages/parser: Babel-based AST parser (JS/TS) + regex (Python)
- packages/llm: OpenAI/Anthropic provider abstraction + prompt pipeline
- packages/diagrams: Mermaid architecture & dependency graph generators
- packages/database: Prisma schema (PostgreSQL)
- Docker multi-stage build (web + worker targets)

All packages compile successfully with tsc and next build.

packages/shared/src/index.ts

@@ -0,0 +1,24 @@
+export type {
+  CloneResult,
+  CloneMetadata,
+  FileNode,
+  FunctionNode,
+  ClassNode,
+  ClassProperty,
+  ImportNode,
+  ExportNode,
+  CodeStructure,
+  ModuleNode,
+  DetectedPattern,
+  DependencyEdge,
+  GeneratedDocs,
+  DocsOverview,
+  DocsModule,
+  DocsPatterns,
+  DocsGettingStarted,
+  Generation,
+  GenerationStatus,
+  LLMMessage,
+  LLMOptions,
+  LLMProviderConfig,
+} from "./types.js";