M4: agent-run job queue + worker drain (Increment 1)

SharedKernel: IWorkerModule seam (RegisterWorker runs in the worker host only).
Bootstrap: AddTeamUpWorkerServices; the worker host now wires it.

Assembler module (schema "assembler", InitialAssembler migration):
- Job (Pending→Processing→Done/Failed) + AgentRun (Queued→Running→Completed/Failed) entities.
- JobQueue: enqueue + ClaimNextAsync using `FOR UPDATE SKIP LOCKED` in a transaction.
- AgentRunExecutor (Increment-1 placeholder — real assemble/model/parse lands in Increment 2).
- JobProcessor BackgroundService drains the queue on the worker host (web off the model path).
- POST /api/assembler/runs enqueues a run; GET /api/assembler/runs/{id} reads it.

Verified: build green; ArchitectureTests 8/8 (Assembler references only SharedKernel);
IntegrationTests 28/28 incl. enqueue→claim(SKIP LOCKED)→process→Completed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Modules/TeamUp.Modules.Assembler/Domain/AgentRun.cs

@@ -0,0 +1,72 @@
+using TeamUp.SharedKernel.Domain;
+
+namespace TeamUp.Modules.Assembler.Domain;
+
+internal enum AgentRunStatus
+{
+    Queued,
+    Running,
+    Completed,
+    Failed,
+}
+
+/// <summary>
+/// One execution of an AI seat against a task: the assembled prompt, the raw model output, the
+/// parsed action + risk tag, and the reasoning/assembly trace. Nothing executes off this in M4 —
+/// the action gate (M5) decides whether the parsed action runs or waits in review.
+/// </summary>
+internal sealed class AgentRun : Entity
+{
+    public Guid SeatId { get; private set; }
+    public Guid WorkItemId { get; private set; }
+    public Guid? AgentId { get; private set; }
+    public AgentRunStatus Status { get; private set; }
+    public string? Prompt { get; private set; }
+    public string? Output { get; private set; }
+    public string? ActionType { get; private set; }
+    public string? ActionRisk { get; private set; }
+    public string? ResultJson { get; private set; }
+    public string? Trace { get; private set; }
+    public string? Error { get; private set; }
+    public long? LatencyMs { get; private set; }
+    public DateTimeOffset CreatedAtUtc { get; private set; }
+    public DateTimeOffset? CompletedAtUtc { get; private set; }
+
+    private AgentRun()
+    {
+    }
+
+    public AgentRun(Guid seatId, Guid workItemId, DateTimeOffset createdAtUtc)
+    {
+        SeatId = seatId;
+        WorkItemId = workItemId;
+        Status = AgentRunStatus.Queued;
+        CreatedAtUtc = createdAtUtc;
+    }
+
+    public void Start(Guid? agentId, string prompt, string? trace)
+    {
+        Status = AgentRunStatus.Running;
+        AgentId = agentId;
+        Prompt = prompt;
+        Trace = trace;
+    }
+
+    public void Complete(string output, string actionType, string actionRisk, string? resultJson, long latencyMs, DateTimeOffset nowUtc)
+    {
+        Status = AgentRunStatus.Completed;
+        Output = output;
+        ActionType = actionType;
+        ActionRisk = actionRisk;
+        ResultJson = resultJson;
+        LatencyMs = latencyMs;
+        CompletedAtUtc = nowUtc;
+    }
+
+    public void Fail(string error, DateTimeOffset nowUtc)
+    {
+        Status = AgentRunStatus.Failed;
+        Error = error;
+        CompletedAtUtc = nowUtc;
+    }
+}