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>

docs/scratchpads/orch-113-coordinator.md

@@ -0,0 +1,79 @@
+# Issue ORCH-113: Coordinator API client
+
+## Objective
+
+Implement HTTP client for calling coordinator quality gates from orchestrator service.
+
+## Approach
+
+1. Create CoordinatorClientService in NestJS with proper dependency injection
+2. Use native fetch API for HTTP calls (Node.js 18+ built-in)
+3. Integrate with ConfigService for COORDINATOR_URL configuration
+4. Implement POST /api/quality/check endpoint call
+5. Add retry logic for coordinator unavailable scenarios
+6. Create comprehensive unit tests with mocked fetch
+
+## API Contract
+
+```typescript
+POST /api/quality/check
+Request: {
+  taskId: string,
+  agentId: string,
+  files: string[],
+  diffSummary: string
+}
+Response: {
+  approved: boolean,
+  gate: string,
+  message?: string,
+  details?: Record<string, unknown>
+}
+```
+
+## Progress
+
+- [x] Read requirements from M6-NEW-ISSUES-TEMPLATES.md
+- [x] Understand coordinator and orchestrator structure
+- [x] Identify coordinator is Python/FastAPI, orchestrator is NestJS
+- [x] Create scratchpad
+- [x] Add COORDINATOR_URL to orchestrator.config.ts
+- [x] Write failing tests for CoordinatorClientService (RED phase)
+- [x] Implement CoordinatorClientService (GREEN phase)
+- [x] Ensure ≥85% test coverage (96.61% statements, 90% branches, 100% lines)
+- [x] Update CoordinatorModule to export the service
+- [x] Update AppModule to import CoordinatorModule
+- [x] Verify TypeScript compilation succeeds for coordinator files
+- [x] Create Gitea issue #248 and close it
+
+## Summary
+
+Successfully implemented ORCH-113 following strict TDD principles. The coordinator API client is fully functional with:
+
+- POST /api/quality/check endpoint integration
+- Retry logic with exponential backoff (3 attempts)
+- Comprehensive error handling
+- 96.61% statement coverage, 90% branch coverage, 100% line coverage
+- 15 passing unit tests
+- Full NestJS integration via CoordinatorModule
+
+The service is ready for use by ORCH-114 (Quality gate callbacks) and ORCH-115 (Task dispatch).
+
+## Testing
+
+- Mock fetch for all HTTP calls
+- Test success scenario (approved=true)
+- Test rejection scenario (approved=false)
+- Test coordinator unavailable (connection error)
+- Test retry logic
+- Test invalid responses
+- Test timeout scenarios
+
+## Notes
+
+- Coordinator runs on port 8000 (Python/FastAPI)
+- Orchestrator runs on port 3001 (NestJS)
+- Using native fetch API (available in Node 18+)
+- Retry strategy: 3 attempts with exponential backoff
+- ConfigService is already set up in app.module.ts
+- Need to extend orchestrator.config.ts with coordinatorUrl