The web UI was linking to /v1/ REST API paths that aren't served
through nginx. Added SVG/JPG/PDF rendering and share link endpoints
directly to the web server so everything works through port 443.
- Add render.go with SVG, JPG, PDF handlers for auth and share paths
- Register render routes and share management routes in web server
- Update template links from /v1/... to /notebooks/... paths
- Add share link creation, display, and revocation to notebook view
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
