Consolidate tools into a secure Docker architecture with landing page

- Implement a central reverse proxy (Nginx) with Basic Auth on port 8090.
- Create a unified landing page (dashboard) to access B2B Assistant and Market Intelligence.
- Update frontends with relative API paths and base paths for subdirectory routing (/b2b/, /market/).
- Optimize Docker builds with .dockerignore and a Python-based image for market-backend.
- Enable code sideloading for Python logic via Docker volumes.
- Fix TypeScript errors in general-market-intelligence regarding ImportMeta.

general-market-intelligence/vite-env.d.ts

@@ -0,0 +1,10 @@
+/// <reference types="vite/client" />
+
+interface ImportMetaEnv {
+  readonly VITE_API_BASE_URL: string;
+  // more env variables...
+}
+
+interface ImportMeta {
+  readonly env: ImportMetaEnv;
+}