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).

tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/SiteRuntimeOptionsValidatorTests.cs

@@ -201,4 +201,46 @@ public class SiteRuntimeOptionsValidatorTests
         Assert.True(result.Failed);
         Assert.Contains("TagSubscribeInFlightCeilingMs", result.FailureMessage);
     }
+
+    [Fact]
+    public void ScriptFileAccess_DefaultsToDisabled_AndIsValid()
+    {
+        var options = new SiteRuntimeOptions();
+        Assert.Empty(options.ScriptFileAccess.AllowedRoots);
+        Assert.True(Validate(options).Succeeded);
+    }
+
+    [Fact]
+    public void ScriptFileAccess_RelativeRoot_IsRejected()
+    {
+        var options = new SiteRuntimeOptions();
+        options.ScriptFileAccess.AllowedRoots.Add("recipes");
+
+        var result = Validate(options);
+
+        Assert.True(result.Failed);
+        Assert.Contains("ScriptFileAccess:AllowedRoots:0", result.FailureMessage);
+    }
+
+    [Fact]
+    public void ScriptFileAccess_AbsoluteRoot_IsAccepted()
+    {
+        var options = new SiteRuntimeOptions();
+        options.ScriptFileAccess.AllowedRoots.Add(Path.GetTempPath());
+        Assert.True(Validate(options).Succeeded);
+    }
+
+    [Theory]
+    [InlineData(0L)]
+    [InlineData(64L * 1024 * 1024 + 1)]
+    public void ScriptFileAccess_MaxFileBytesOutOfRange_IsRejected(long max)
+    {
+        var options = new SiteRuntimeOptions();
+        options.ScriptFileAccess.MaxFileBytes = max;
+
+        var result = Validate(options);
+
+        Assert.True(result.Failed);
+        Assert.Contains("ScriptFileAccess:MaxFileBytes", result.FailureMessage);
+    }
 }