feat(scripts): read-only, allow-listed Files global for site scripts; Delmia test receiver parses recipe files

Script file access (design docs/plans/2026-09-28-script-file-access-design.md): Files.ReadTextAsync /
ReadLinesAsync / ExistsAsync on site ScriptGlobals (+ Instance.Files), backed by the site-singleton
ScriptFileReader. The one host-mediated exception to the System.IO ban - scripts still never name a
System.IO type. OFF by default: ScadaBridge:SiteRuntime:ScriptFileAccess:AllowedRoots (empty = every call
throws Disabled) + MaxFileBytes (1 MiB, validated 1..64 MiB, roots must be absolute). Guard: fully
qualified, no device paths / ADS, canonical path strictly inside a root (directory-boundary match), no
reparse point on the file or any directory below the root, size cap before and during the read.
Errors are one Commons type, ScriptFileAccessException(+ScriptFileAccessFailure); Commons.Types.Scripts
joins the default script imports on every surface so it binds by short name. Mirrored on
ScriptCompileSurface (CompileFiles, parity-pinned) and the Test Run sandbox (binds, refuses Disabled).
Inbound (central) scripts do not get it.

Rig: docker/recipes (sample RecipeValueName,RecipeValue files incl. an invalid one) bind-mounted
read-only at /app/recipes on both site-a nodes with AllowedRoots [/app/recipes]. The TestMesMachine
SimDelmiaRecipe simulator now reads + parses the downloaded file, converts each value to its recipe tag's
type and loads it all-or-nothing (14 new TestDelmiaReceiver attributes); verify-mes-test-machine.sh
group A covers accept / re-download / invalid lines / NotFound / OutsideAllowedRoots, VERIFY_GROUPS
selects groups (rig: AD).

src/ZB.MOM.WW.ScadaBridge.CentralUI/ScriptAnalysis/SandboxScriptHost.cs

@@ -96,6 +96,46 @@ public class SandboxScriptHost
     /// <c>Log</c> and <c>Instance.Log</c> are the same object here too.
     /// </summary>
     public SandboxLog Log => Instance.Log;
+
+    /// <summary>
+    /// Sandbox mirror of the site runtime's <c>Files</c> global (design 2026-09-28), so a script
+    /// that reads a file BINDS in the Test Run editor. The central sandbox has no access to a
+    /// site node's filesystem, so every call throws the same
+    /// <see cref="ScriptFileAccessException"/> (<see cref="ScriptFileAccessFailure.Disabled"/>) a
+    /// site without configured roots throws — a script's own error handling runs as it would there.
+    /// </summary>
+    public SandboxFilesAccessor Files => Instance.Files;
+}
+
+/// <summary>
+/// Sandbox mirror of the SiteRuntime <c>FilesAccessor</c>: binds identically, refuses at run time.
+/// </summary>
+public class SandboxFilesAccessor
+{
+    private const string Message =
+        "Files.* reads the SITE node's filesystem (under ScadaBridge:SiteRuntime:ScriptFileAccess:AllowedRoots), " +
+        "which the central Test Run sandbox cannot reach — deploy to a site to exercise file-reading scripts.";
+
+    /// <summary>Mirrors <c>FilesAccessor.ReadTextAsync</c>; always refused in the sandbox.</summary>
+    /// <param name="path">The file path.</param>
+    /// <param name="cancellationToken">Unused in the sandbox.</param>
+    /// <returns>Never returns.</returns>
+    public Task<string> ReadTextAsync(string path, CancellationToken cancellationToken = default)
+        => throw new ScriptFileAccessException(ScriptFileAccessFailure.Disabled, Message);
+
+    /// <summary>Mirrors <c>FilesAccessor.ReadLinesAsync</c>; always refused in the sandbox.</summary>
+    /// <param name="path">The file path.</param>
+    /// <param name="cancellationToken">Unused in the sandbox.</param>
+    /// <returns>Never returns.</returns>
+    public Task<IReadOnlyList<string>> ReadLinesAsync(string path, CancellationToken cancellationToken = default)
+        => throw new ScriptFileAccessException(ScriptFileAccessFailure.Disabled, Message);
+
+    /// <summary>Mirrors <c>FilesAccessor.ExistsAsync</c>; always refused in the sandbox.</summary>
+    /// <param name="path">The file path.</param>
+    /// <param name="cancellationToken">Unused in the sandbox.</param>
+    /// <returns>Never returns.</returns>
+    public Task<bool> ExistsAsync(string path, CancellationToken cancellationToken = default)
+        => throw new ScriptFileAccessException(ScriptFileAccessFailure.Disabled, Message);
 }
 
 /// <summary>
@@ -263,6 +303,9 @@ public class SandboxInstanceContext
     /// </summary>
     public SandboxLog Log { get; } = new();
 
+    /// <summary>Sandbox mirror of <c>ScriptRuntimeContext.Files</c> (design 2026-09-28); always refuses.</summary>
+    public SandboxFilesAccessor Files { get; } = new();
+
     /// <summary>
     /// Initializes a new instance of the SandboxInstanceContext.
     /// </summary>