feat(pipeline): add runnable artifact pipeline increment

[Change Nature]
- This commit adds the first runnable increment of the F# artifact
  pipeline: CLI, server, frontend bundle, stage fixture, and tests.
  It is feature work, not a bug fix.

[New Capability]
- CLI `run` executes the three-step Blender fixture through the process
  bridge and writes GLBs, step logs, events, and a manifest; `verify`
  validates a manifest without Blender.
- Server exposes run start, run-scoped SSE, artifact manifest/file
  routes, and serves the Fable frontend from its build output.
- Frontend starts runs, follows run-scoped SSE progress, and links the
  artifact manifest on completion.

[Implementation]
- Shared layer holds domain, run state, replay, and artifact contracts;
  Modeling holds the pipeline, 120s bridge timeout, and result-file
  protocol; stage/blender/fixture.py owns geometry in Python (bpy owns
  geometry, F# owns orchestration).
- Fable bundle is regenerated into public/ and copied by the server
  project; solution includes all projects with warnings-as-errors.
- README documents build, Fable, server, interpreter/env, fixture
  limitations, and current verification status.

[Impact]
- Verified: 40/40 solution tests pass; Release build 0 warnings/errors;
  real CLI run with bpy 5.0.1 produced 3 GLBs, 3 logs, and a
  verify-clean manifest; isolated-port server smoke flow succeeded.
- Not yet verified: browser end-to-end behavior and production
  fidelity. Artifacts and caches are gitignored.

2 files changed, 91 insertions, 0 deletions

diff --git a/tests/SomhairlesDream.Cli.Tests/ArgumentsTests.fs b/tests/SomhairlesDream.Cli.Tests/ArgumentsTests.fs
new file mode 100644
index 0000000..f55762e
--- /dev/null
+++ b/tests/SomhairlesDream.Cli.Tests/ArgumentsTests.fs
@@ -0,0 +1,70 @@
+module SomhairlesDream.Cli.Tests.ArgumentsTests
+
+open Xunit
+open SomhairlesDream.Cli
+
+let private expectOk = function
+    | Ok value -> value
+    | Error message -> failwith message
+
+let private expectError = function
+    | Error message -> message
+    | Ok _ -> failwith "expected an error"
+
+[<Fact>]
+let ``run command applies documented defaults`` () =
+    match Arguments.parse [| "run" |] |> expectOk with
+    | Run options ->
+        Assert.Equal("heritage-001", options.Ids.ProjectId)
+        Assert.Equal("run-001", options.Ids.RunId)
+        Assert.Equal("base-000", options.Ids.BaseId)
+        Assert.Equal("target-003", options.Ids.TargetId)
+        Assert.Equal(".artifacts", options.OutputRoot)
+        Assert.Equal("stage", options.StageRoot)
+        Assert.False(options.Render)
+        Assert.NotEmpty(options.Python)
+    | Verify _
+    | Help -> failwith "expected run command"
+
+[<Fact>]
+let ``run command parses explicit ids and render flag`` () =
+    match
+        Arguments.parse
+            [| "run"
+               "--project-id"
+               "project-x"
+               "--run-id"
+               "run-x"
+               "--base-id"
+               "base-x"
+               "--target-id"
+               "target-x"
+               "--output-root"
+               "out"
+               "--stage-root"
+               "fixtures"
+               "--python"
+               "/tmp/python"
+               "--render" |]
+        |> expectOk with
+    | Run options ->
+        Assert.Equal("project-x", options.Ids.ProjectId)
+        Assert.Equal("run-x", options.Ids.RunId)
+        Assert.Equal("base-x", options.Ids.BaseId)
+        Assert.Equal("target-x", options.Ids.TargetId)
+        Assert.Equal("out", options.OutputRoot)
+        Assert.Equal("fixtures", options.StageRoot)
+        Assert.Equal("/tmp/python", options.Python)
+        Assert.True(options.Render)
+    | Verify _
+    | Help -> failwith "expected run command"
+
+[<Fact>]
+let ``verify command requires exactly one manifest path`` () =
+    match Arguments.parse [| "verify"; "run"; "extra" |] |> expectError with
+    | message -> Assert.Contains("manifest", message)
+
+[<Fact>]
+let ``arguments reject unsafe resource ids`` () =
+    match Arguments.parse [| "run"; "--project-id"; "../escape" |] |> expectError with
+    | message -> Assert.Contains("resource id", message)
diff --git a/tests/SomhairlesDream.Cli.Tests/SomhairlesDream.Cli.Tests.fsproj b/tests/SomhairlesDream.Cli.Tests/SomhairlesDream.Cli.Tests.fsproj
new file mode 100644
index 0000000..461d5eb
--- /dev/null
+++ b/tests/SomhairlesDream.Cli.Tests/SomhairlesDream.Cli.Tests.fsproj
@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="../../src/SomhairlesDream.Cli/SomhairlesDream.Cli.fsproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="ArgumentsTests.fs" />
+  </ItemGroup>
+</Project>