feat(#93): implement agent spawn via federation

Implements FED-010: Agent Spawn via Federation feature that enables
spawning and managing Claude agents on remote federated Mosaic Stack
instances via COMMAND message type.

Features:
- Federation agent command types (spawn, status, kill)
- FederationAgentService for handling agent operations
- Integration with orchestrator's agent spawner/lifecycle services
- API endpoints for spawning, querying status, and killing agents
- Full command routing through federation COMMAND infrastructure
- Comprehensive test coverage (12/12 tests passing)

Architecture:
- Hub → Spoke: Spawn agents on remote instances
- Command flow: FederationController → FederationAgentService →
  CommandService → Remote Orchestrator
- Response handling: Remote orchestrator returns agent status/results
- Security: Connection validation, signature verification

Files created:
- apps/api/src/federation/types/federation-agent.types.ts
- apps/api/src/federation/federation-agent.service.ts
- apps/api/src/federation/federation-agent.service.spec.ts

Files modified:
- apps/api/src/federation/command.service.ts (agent command routing)
- apps/api/src/federation/federation.controller.ts (agent endpoints)
- apps/api/src/federation/federation.module.ts (service registration)
- apps/orchestrator/src/api/agents/agents.controller.ts (status endpoint)
- apps/orchestrator/src/api/agents/agents.module.ts (lifecycle integration)

Testing:
- 12/12 tests passing for FederationAgentService
- All command service tests passing
- TypeScript compilation successful
- Linting passed

Refs #93

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/layouts/__tests__/layouts.service.spec.ts

@@ -114,9 +114,9 @@ describe("LayoutsService", () => {
         .mockResolvedValueOnce(null) // No default
         .mockResolvedValueOnce(null); // No layouts
 
-      await expect(
-        service.findDefault(mockWorkspaceId, mockUserId)
-      ).rejects.toThrow(NotFoundException);
+      await expect(service.findDefault(mockWorkspaceId, mockUserId)).rejects.toThrow(
+        NotFoundException
+      );
     });
   });
 
@@ -139,9 +139,9 @@ describe("LayoutsService", () => {
     it("should throw NotFoundException if layout not found", async () => {
       prisma.userLayout.findUnique.mockResolvedValue(null);
 
-      await expect(
-        service.findOne("invalid-id", mockWorkspaceId, mockUserId)
-      ).rejects.toThrow(NotFoundException);
+      await expect(service.findOne("invalid-id", mockWorkspaceId, mockUserId)).rejects.toThrow(
+        NotFoundException
+      );
     });
   });
 
@@ -221,12 +221,7 @@ describe("LayoutsService", () => {
         })
       );
 
-      const result = await service.update(
-        "layout-1",
-        mockWorkspaceId,
-        mockUserId,
-        updateDto
-      );
+      const result = await service.update("layout-1", mockWorkspaceId, mockUserId, updateDto);
 
       expect(result).toBeDefined();
       expect(mockFindUnique).toHaveBeenCalled();
@@ -244,9 +239,9 @@ describe("LayoutsService", () => {
         })
       );
 
-      await expect(
-        service.update("invalid-id", mockWorkspaceId, mockUserId, {})
-      ).rejects.toThrow(NotFoundException);
+      await expect(service.update("invalid-id", mockWorkspaceId, mockUserId, {})).rejects.toThrow(
+        NotFoundException
+      );
     });
   });
 
@@ -269,9 +264,9 @@ describe("LayoutsService", () => {
     it("should throw NotFoundException if layout not found", async () => {
       prisma.userLayout.findUnique.mockResolvedValue(null);
 
-      await expect(
-        service.remove("invalid-id", mockWorkspaceId, mockUserId)
-      ).rejects.toThrow(NotFoundException);
+      await expect(service.remove("invalid-id", mockWorkspaceId, mockUserId)).rejects.toThrow(
+        NotFoundException
+      );
     });
   });
 });