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/cron/cron.service.spec.ts

@@ -83,8 +83,20 @@ describe("CronService", () => {
     it("should return all schedules for a workspace", async () => {
       const workspaceId = "ws-123";
       const expectedSchedules = [
-        { id: "cron-1", workspaceId, expression: "0 9 * * *", command: "morning briefing", enabled: true },
-        { id: "cron-2", workspaceId, expression: "0 17 * * *", command: "evening summary", enabled: true },
+        {
+          id: "cron-1",
+          workspaceId,
+          expression: "0 9 * * *",
+          command: "morning briefing",
+          enabled: true,
+        },
+        {
+          id: "cron-2",
+          workspaceId,
+          expression: "0 17 * * *",
+          command: "evening summary",
+          enabled: true,
+        },
       ];
 
       mockPrisma.cronSchedule.findMany.mockResolvedValue(expectedSchedules);