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/common/utils/query-builder.spec.ts

@@ -27,18 +27,14 @@ describe("QueryBuilder", () => {
     it("should handle single field", () => {
       const result = QueryBuilder.buildSearchFilter("test", ["title"]);
       expect(result).toEqual({
-        OR: [
-          { title: { contains: "test", mode: "insensitive" } },
-        ],
+        OR: [{ title: { contains: "test", mode: "insensitive" } }],
       });
     });
 
     it("should trim search query", () => {
       const result = QueryBuilder.buildSearchFilter("  test  ", ["title"]);
       expect(result).toEqual({
-        OR: [
-          { title: { contains: "test", mode: "insensitive" } },
-        ],
+        OR: [{ title: { contains: "test", mode: "insensitive" } }],
       });
     });
   });
@@ -56,26 +52,17 @@ describe("QueryBuilder", () => {
 
     it("should build multi-field sort", () => {
       const result = QueryBuilder.buildSortOrder("priority,dueDate", SortOrder.DESC);
-      expect(result).toEqual([
-        { priority: "desc" },
-        { dueDate: "desc" },
-      ]);
+      expect(result).toEqual([{ priority: "desc" }, { dueDate: "desc" }]);
     });
 
     it("should handle mixed sorting with custom order per field", () => {
       const result = QueryBuilder.buildSortOrder("priority:asc,dueDate:desc");
-      expect(result).toEqual([
-        { priority: "asc" },
-        { dueDate: "desc" },
-      ]);
+      expect(result).toEqual([{ priority: "asc" }, { dueDate: "desc" }]);
     });
 
     it("should use default order when not specified per field", () => {
       const result = QueryBuilder.buildSortOrder("priority,dueDate", SortOrder.ASC);
-      expect(result).toEqual([
-        { priority: "asc" },
-        { dueDate: "asc" },
-      ]);
+      expect(result).toEqual([{ priority: "asc" }, { dueDate: "asc" }]);
     });
   });