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/events/events.controller.spec.ts

@@ -63,11 +63,7 @@ describe("EventsController", () => {
       const result = await controller.create(createDto, mockWorkspaceId, mockUser);
 
       expect(result).toEqual(mockEvent);
-      expect(service.create).toHaveBeenCalledWith(
-        mockWorkspaceId,
-        mockUserId,
-        createDto
-      );
+      expect(service.create).toHaveBeenCalledWith(mockWorkspaceId, mockUserId, createDto);
     });
 
     it("should pass undefined workspaceId to service (validation handled by guards in production)", async () => {
@@ -153,7 +149,12 @@ describe("EventsController", () => {
 
       await controller.update(mockEventId, updateDto, undefined as any, mockUser);
 
-      expect(mockEventsService.update).toHaveBeenCalledWith(mockEventId, undefined, mockUserId, updateDto);
+      expect(mockEventsService.update).toHaveBeenCalledWith(
+        mockEventId,
+        undefined,
+        mockUserId,
+        updateDto
+      );
     });
   });
 
@@ -163,11 +164,7 @@ describe("EventsController", () => {
 
       await controller.remove(mockEventId, mockWorkspaceId, mockUser);
 
-      expect(service.remove).toHaveBeenCalledWith(
-        mockEventId,
-        mockWorkspaceId,
-        mockUserId
-      );
+      expect(service.remove).toHaveBeenCalledWith(mockEventId, mockWorkspaceId, mockUserId);
     });
 
     it("should pass undefined workspaceId to service (validation handled by guards in production)", async () => {