feat: initial monorepo scaffold - Next.js 15 + Prisma + Python SDK stubs

- Turborepo monorepo with apps/web and packages/database, sdk-python
- Next.js 15 app with professional landing page (dark theme, emerald accent)
- Prisma schema: Trace, DecisionPoint, Span, Event models with full indexing
- Docker Compose: web (port 4200), postgres:16, redis:7, migrate service
- Python SDK package stubs: init, trace decorator, log_decision, integrations
- Multi-stage Dockerfile for standalone Next.js production build

apps/web/next.config.mjs

@@ -0,0 +1,7 @@
+/** @type {import('next').NextConfig} */
+const config = {
+  transpilePackages: ["@agentlens/database"],
+  output: "standalone",
+};
+
+export default config;