feat(cli): bundle export / preview / import for Transport (#24)

Three new CLI commands automate the Transport feature end-to-end:

  scadalink bundle export  --output FILE --passphrase X [--all | --templates A,B ...] [--include-dependencies] [--source-environment NAME]
  scadalink bundle preview --input FILE  --passphrase X
  scadalink bundle import  --input FILE  --passphrase X [--on-conflict skip|overwrite|rename]

Wire format: bundle bytes travel as base64 inside the existing
/management JSON envelope -- no new endpoints, no streaming plumbing.
The 100 MB raw cap inflates to ~140 MB base64; per-request body size
on the management endpoint is raised to 200 MB via the
IHttpMaxRequestBodySizeFeature.

Server side: three new command records in
ScadaLink.Commons.Messages.Management (auto-discovered by the
existing ManagementCommandRegistry), ManagementActor dispatch and
role rules (Export=Design, Preview/Import=Admin), and three
handlers that delegate to the existing IBundleExporter /
IBundleImporter services with name-keyed selection resolution.
Per-bundle CLI timeout bumped to 5 min for large exports.

Conflict policy on import is a single global flag for all Modified
rows; Identical rows always Skip, New rows always Add, Blocker rows
abort. Rename mints a per-bundle timestamp suffix.

src/ScadaLink.Commons/Messages/Management/TransportCommands.cs

@@ -0,0 +1,62 @@
+using ScadaLink.Commons.Types.Transport;
+
+namespace ScadaLink.Commons.Messages.Management;
+
+/// <summary>
+/// Exports a bundle. Names rather than IDs in the selection so test scripts can
+/// be written without an ID lookup step. <c>All=true</c> overrides the per-type
+/// name lists and exports every entity of every supported type.
+/// </summary>
+public sealed record ExportBundleCommand(
+    bool All,
+    IReadOnlyList<string>? TemplateNames,
+    IReadOnlyList<string>? SharedScriptNames,
+    IReadOnlyList<string>? ExternalSystemNames,
+    IReadOnlyList<string>? DatabaseConnectionNames,
+    IReadOnlyList<string>? NotificationListNames,
+    IReadOnlyList<string>? SmtpConfigurationNames,
+    IReadOnlyList<string>? ApiKeyNames,
+    IReadOnlyList<string>? ApiMethodNames,
+    bool IncludeDependencies,
+    string? Passphrase,
+    string SourceEnvironment);
+
+/// <summary>
+/// Bundle body returned as base64-encoded ZIP. <see cref="ByteCount"/> is the
+/// pre-encoded size for sanity checks against the configured bundle cap.
+/// </summary>
+public sealed record ExportBundleResult(
+    string Base64Bundle,
+    int ByteCount);
+
+/// <summary>
+/// Loads a bundle and returns its preview without applying anything. Useful
+/// for tests that want to assert on the diff shape before committing.
+/// </summary>
+public sealed record PreviewBundleCommand(
+    string Base64Bundle,
+    string? Passphrase);
+
+public sealed record PreviewBundleResult(
+    IReadOnlyList<ImportPreviewItem> Items,
+    int AddCount,
+    int ModifiedCount,
+    int IdenticalCount,
+    int BlockerCount);
+
+/// <summary>
+/// Loads, previews, and applies a bundle in a single call. The diff is built
+/// internally; every <see cref="ConflictKind.Modified"/> row is resolved with
+/// <see cref="DefaultConflictPolicy"/>, every <see cref="ConflictKind.New"/>
+/// row gets <see cref="ResolutionAction.Add"/>, every
+/// <see cref="ConflictKind.Identical"/> row gets <see cref="ResolutionAction.Skip"/>,
+/// and any <see cref="ConflictKind.Blocker"/> row fails the call.
+/// <para>
+/// Valid <see cref="DefaultConflictPolicy"/> values: <c>"skip"</c>,
+/// <c>"overwrite"</c>, <c>"rename"</c>. Rename mints a unique suffix per row.
+/// </para>
+/// </summary>
+public sealed record ImportBundleCommand(
+    string Base64Bundle,
+    string? Passphrase,
+    string DefaultConflictPolicy);