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/knowledge/services/graph.service.spec.ts

@@ -271,9 +271,7 @@ describe("GraphService", () => {
     });
 
     it("should filter by status", async () => {
-      const entries = [
-        { ...mockEntry, id: "entry-1", status: "PUBLISHED", tags: [] },
-      ];
+      const entries = [{ ...mockEntry, id: "entry-1", status: "PUBLISHED", tags: [] }];
 
       mockPrismaService.knowledgeEntry.findMany.mockResolvedValue(entries);
       mockPrismaService.knowledgeLink.findMany.mockResolvedValue([]);
@@ -351,9 +349,7 @@ describe("GraphService", () => {
         { id: "entry-1", slug: "entry-1", title: "Entry 1", link_count: "5" },
         { id: "entry-2", slug: "entry-2", title: "Entry 2", link_count: "3" },
       ]);
-      mockPrismaService.knowledgeEntry.findMany.mockResolvedValue([
-        { id: "orphan-1" },
-      ]);
+      mockPrismaService.knowledgeEntry.findMany.mockResolvedValue([{ id: "orphan-1" }]);
 
       const result = await service.getGraphStats("workspace-1");