Add a new `shared_network` option to workspaces and workspace templates
that controls network configuration for container (nspawn) workspaces:
- When true (default): Share host network, bind-mount /etc/resolv.conf
for DNS resolution
- When false: Use isolated networking (--network-veth) for Tailscale
or other custom network configurations
This fixes DNS resolution issues in container workspaces that don't use
Tailscale by properly sharing the host's DNS configuration.
Changes:
- Add shared_network field to Workspace and WorkspaceTemplate structs
- Update nspawn command building to use shared_network setting
- Add UI toggles in workspace template editor and workspace settings
- Update API types and endpoints
5c2f898234