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.

1 files changed, 102 insertions, 0 deletions

diff --git a/src/SomhairlesDream.Shared/Domain.fs b/src/SomhairlesDream.Shared/Domain.fs
new file mode 100644
index 0000000..fd229fa
--- /dev/null
+++ b/src/SomhairlesDream.Shared/Domain.fs
@@ -0,0 +1,102 @@
+namespace SomhairlesDream.Shared
+
+open System
+
+[<RequireQualifiedAccess>]
+type RunStatus =
+    | Idle = 0
+    | Queued = 1
+    | Running = 2
+    | Succeeded = 3
+    | Failed = 4
+    | Stale = 5
+
+type Vector3 =
+    { X: float
+      Y: float
+      Z: float }
+
+type MeshSnapshot =
+    { Version: int
+      Label: string
+      Vertices: Vector3 array
+      Faces: int array array }
+
+type LiveSnapshot =
+    { ProjectId: string
+      RunId: string
+      Status: RunStatus
+      CurrentVersion: int
+      TargetVersion: int
+      HeartbeatAt: DateTimeOffset option
+      UpdatedAt: DateTimeOffset
+      Message: string
+      Mesh: MeshSnapshot option
+      NextDesignRunScheduled: bool }
+
+module MeshData =
+    let positionData (mesh: MeshSnapshot) =
+        mesh.Vertices
+        |> Array.collect (fun vertex -> [| vertex.X; vertex.Y; vertex.Z |])
+
+    let triangleIndices (mesh: MeshSnapshot) =
+        mesh.Faces
+        |> Array.collect (fun face ->
+            if face.Length < 3 then
+                [||]
+            else
+                [| for index in 1 .. face.Length - 2 do
+                       yield face[0]
+                       yield face[index]
+                       yield face[index + 1] |])
+
+module RunState =
+    let initial projectId runId now =
+        { ProjectId = projectId
+          RunId = runId
+          Status = RunStatus.Idle
+          CurrentVersion = 0
+          TargetVersion = 0
+          HeartbeatAt = None
+          UpdatedAt = now
+          Message = "等待设计运行"
+          Mesh = None
+          NextDesignRunScheduled = false }
+
+    let start now state =
+        let targetVersion = state.TargetVersion + 1
+
+        { state with
+            Status = RunStatus.Running
+            TargetVersion = targetVersion
+            HeartbeatAt = Some now
+            UpdatedAt = now
+            Message = $"正在生成第 {targetVersion} 版几何"
+            NextDesignRunScheduled = false }
+
+    let heartbeat now state =
+        if state.Status = RunStatus.Running then
+            { state with
+                HeartbeatAt = Some now
+                UpdatedAt = now }
+        else
+            state
+
+    let statusAt timeout now state =
+        match state.HeartbeatAt with
+        | Some heartbeatAt when state.Status = RunStatus.Running && now - heartbeatAt > timeout ->
+            { state with
+                Status = RunStatus.Stale
+                UpdatedAt = now
+                Message = "心跳超时，等待重连" }
+        | _ -> state
+
+    let publish now mesh state =
+        { state with
+            Status = RunStatus.Succeeded
+            CurrentVersion = mesh.Version
+            HeartbeatAt = Some now
+            UpdatedAt = now
+            Message = $"已发布{mesh.Label}"
+            Mesh = Some mesh
+            NextDesignRunScheduled = false }