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.

apps/worker/src/jobs/generate.ts

@@ -0,0 +1,26 @@
+import type { CodeStructure, GeneratedDocs } from "@codeboard/shared";
+import { createProvider, generateDocumentation } from "@codeboard/llm";
+
+export async function generateDocs(
+  codeStructure: CodeStructure,
+  onProgress?: (stage: string, progress: number) => void
+): Promise<GeneratedDocs> {
+  const apiKey =
+    process.env.OPENAI_API_KEY ?? process.env.ANTHROPIC_API_KEY ?? "";
+
+  if (!apiKey) {
+    throw new Error(
+      "No LLM API key configured. Set OPENAI_API_KEY or ANTHROPIC_API_KEY."
+    );
+  }
+
+  const providerType = process.env.OPENAI_API_KEY ? "openai" : "anthropic";
+  const provider = createProvider({
+    provider: providerType,
+    apiKey,
+    model: process.env.LLM_MODEL,
+    baseUrl: process.env.LLM_BASE_URL,
+  });
+
+  return generateDocumentation(codeStructure, provider, onProgress);
+}