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/2-postgresql-pgvector-schema.md

@@ -1,9 +1,11 @@
 # Issue #2: PostgreSQL 17 + pgvector Schema
 
 ## Objective
+
 Design and implement the PostgreSQL 17 database schema with pgvector extension for Mosaic Stack.
 
 ## Approach
+
 1. **Docker Infrastructure** - Build PostgreSQL 17 container with pgvector extension
 2. **Prisma ORM** - Define schema with 8 core models (User, Workspace, Task, Event, Project, etc.)
 3. **Multi-tenant Design** - All tables indexed by workspace_id for RLS preparation
@@ -11,6 +13,7 @@ Design and implement the PostgreSQL 17 database schema with pgvector extension f
 5. **NestJS Integration** - PrismaService + EmbeddingsService for database operations
 
 ## Progress
+
 - [x] Plan approved
 - [x] Phase 1: Docker Setup (5 tasks) - COMPLETED
 - [x] Phase 2: Prisma Schema (5 tasks) - COMPLETED
@@ -19,9 +22,11 @@ Design and implement the PostgreSQL 17 database schema with pgvector extension f
 - [x] Phase 5: Build & Verification (2 tasks) - COMPLETED
 
 ## Completion Summary
+
 **Issue #2 successfully completed on 2026-01-28**
 
 ### What Was Delivered
+
 1. **Docker Infrastructure**
    - PostgreSQL 17 with pgvector v0.7.4 (HNSW index enabled)
    - Valkey for caching
@@ -54,19 +59,23 @@ Design and implement the PostgreSQL 17 database schema with pgvector extension f
    - All builds passing with strict TypeScript
 
 ### Database Statistics
+
 - Tables: 8
 - Extensions: uuid-ossp, vector (pgvector 0.7.4)
 - Indexes: 14 total (including 1 HNSW vector index)
 - Seed data: 1 user, 1 workspace, 1 project, 5 tasks, 1 event
 
 ## Testing
+
 - Unit tests for PrismaService (connection lifecycle, health check)
 - Unit tests for EmbeddingsService (store, search, delete operations)
 - Integration test with actual PostgreSQL database
 - Seed data validation via Prisma Studio
 
 ## Notes
+
 ### Design Decisions
+
 - **UUID primary keys** for multi-tenant scalability
 - **Native Prisma enums** mapped to PostgreSQL enums for type safety
 - **`Unsupported("vector(1536)")`** type for pgvector (raw SQL operations)
@@ -74,11 +83,13 @@ Design and implement the PostgreSQL 17 database schema with pgvector extension f
 - **Self-referencing Task** model for subtasks support
 
 ### Key Relations
+
 - User → ownedWorkspaces (1:N), workspaceMemberships (N:M via WorkspaceMember)
 - Workspace → tasks, events, projects, activityLogs, memoryEmbeddings (1:N each)
 - Task → subtasks (self-referencing), project (optional N:1)
 
 ### RLS Preparation (M2 Milestone)
+
 - All tenant tables have workspace_id with index
 - Future: PostgreSQL session variables (app.current_workspace_id, app.current_user_id)
 - Future: RLS policies for workspace isolation