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.

Dockerfile

@@ -0,0 +1,48 @@
+FROM node:20-alpine AS base
+RUN apk add --no-cache git
+WORKDIR /app
+
+FROM base AS deps
+COPY package.json package-lock.json* ./
+COPY apps/web/package.json ./apps/web/
+COPY apps/worker/package.json ./apps/worker/
+COPY packages/shared/package.json ./packages/shared/
+COPY packages/parser/package.json ./packages/parser/
+COPY packages/llm/package.json ./packages/llm/
+COPY packages/diagrams/package.json ./packages/diagrams/
+COPY packages/database/package.json ./packages/database/
+RUN npm install --production=false
+
+FROM base AS builder
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+RUN npx turbo build
+
+FROM base AS web
+RUN addgroup --system --gid 1001 nodejs && \
+    adduser --system --uid 1001 nextjs
+COPY --from=builder --chown=nextjs:nodejs /app/apps/web/.next/standalone ./
+COPY --from=builder --chown=nextjs:nodejs /app/apps/web/.next/static ./apps/web/.next/static
+COPY --from=builder --chown=nextjs:nodejs /app/apps/web/public ./apps/web/public
+USER nextjs
+EXPOSE 3000
+ENV PORT=3000 HOSTNAME="0.0.0.0"
+CMD ["node", "apps/web/server.js"]
+
+FROM base AS worker
+RUN addgroup --system --gid 1001 nodejs && \
+    adduser --system --uid 1001 workeruser
+COPY --from=deps /app/node_modules ./node_modules
+COPY --from=builder /app/apps/worker/dist ./apps/worker/dist
+COPY --from=builder /app/packages/shared/dist ./packages/shared/dist
+COPY --from=builder /app/packages/parser/dist ./packages/parser/dist
+COPY --from=builder /app/packages/llm/dist ./packages/llm/dist
+COPY --from=builder /app/packages/diagrams/dist ./packages/diagrams/dist
+COPY --from=builder /app/package.json ./
+COPY --from=builder /app/apps/worker/package.json ./apps/worker/
+COPY --from=builder /app/packages/shared/package.json ./packages/shared/
+COPY --from=builder /app/packages/parser/package.json ./packages/parser/
+COPY --from=builder /app/packages/llm/package.json ./packages/llm/
+COPY --from=builder /app/packages/diagrams/package.json ./packages/diagrams/
+USER workeruser
+CMD ["node", "apps/worker/dist/index.js"]