Implements Task T21 of the Transport feature. A four-step Blazor wizard
(Select → Review → Encrypt → Download) under /design/transport/export,
gated on AuthorizationPolicies.RequireDesign:
1. Select — TemplateFolderTree (checkbox-mode) plus flat checkbox
lists for shared scripts, external systems, DB connections,
notification lists, SMTP configs, API keys, API methods.
2. Review — runs DependencyResolver, surfaces seed vs auto-included.
"Include all dependencies" toggle re-resolves on flip.
3. Encrypt — passphrase + confirm with strength meter, secret-count
warning over the resolved closure, explicit unencrypted
opt-out path (calls BundleExporter with passphrase=null
so the audit row tags UnencryptedBundleExport).
4. Download— calls IBundleExporter.ExportAsync, streams bytes to the
browser via JS interop (wwwroot/js/transport.js), displays
filename + size + SHA-256 + encryption status.
Source environment is sourced from new TransportOptions.SourceEnvironment
(bound from ScadaLink:Transport:SourceEnvironment, defaults "scadalink"),
filename pattern scadabundle-{env}-{yyyy-MM-dd-HHmmss}.scadabundle.
Tests (bUnit + policy): step 1 group rendering, step 2 dependency
expansion (Pump composes Motor), step 4 full walkthrough verifying
ExportAsync receives the selected ids + authenticated identity, and a
RequireDesign policy-deny test for users without the Design role. Also
unit-pins the filename-sanitisation contract.