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-112-conflicts.md

@@ -1,11 +1,13 @@
 # ORCH-112: Conflict Detection
 
 ## Objective
+
 Implement conflict detection service that detects merge conflicts before pushing to remote. This is the final git integration feature for Phase 3.
 
 ## Approach
 
 ### Architecture
+
 1. **ConflictDetectionService**: NestJS service that:
    - Fetches latest changes from remote before push
    - Detects merge conflicts using simple-git
@@ -13,6 +15,7 @@ Implement conflict detection service that detects merge conflicts before pushing
    - Supports both merge and rebase strategies
 
 ### Conflict Detection Strategy
+
 1. Fetch remote branch
 2. Try merge/rebase in dry-run mode (or check status after fetch)
 3. Detect conflicts by:
@@ -22,6 +25,7 @@ Implement conflict detection service that detects merge conflicts before pushing
 4. Return structured conflict information with file paths and details
 
 ### Integration Points
+
 - Uses GitOperationsService for basic git operations
 - Will be called by orchestrator before push operations
 - Provides retry capability with different strategies
@@ -46,6 +50,7 @@ Implement conflict detection service that detects merge conflicts before pushing
 ## Completion Summary
 
 Implementation completed successfully with all acceptance criteria met:
+
 - ConflictDetectionService implemented with full TDD approach
 - Supports both merge and rebase strategies
 - Comprehensive error handling with ConflictDetectionError
@@ -55,6 +60,7 @@ Implementation completed successfully with all acceptance criteria met:
 - Integrated into GitModule and exported
 
 Files created/modified:
+
 - apps/orchestrator/src/git/conflict-detection.service.ts
 - apps/orchestrator/src/git/conflict-detection.service.spec.ts
 - apps/orchestrator/src/git/types/conflict-detection.types.ts
@@ -65,6 +71,7 @@ Files created/modified:
 ## Testing Strategy
 
 ### Unit Tests (TDD)
+
 1. **No conflicts scenario**:
    - Fetch succeeds
    - No conflicts detected
@@ -89,6 +96,7 @@ Files created/modified:
    - Prevents push if conflicts exist
 
 ### Mock Strategy
+
 - Mock simple-git for all git operations
 - Mock GitOperationsService where needed
 - Test both merge and rebase strategies
@@ -96,6 +104,7 @@ Files created/modified:
 ## Technical Notes
 
 ### Key Methods
+
 ```typescript
 // Check for conflicts before push
 async checkForConflicts(
@@ -118,33 +127,31 @@ async detectConflicts(
 ```
 
 ### Types
+
 ```typescript
 interface ConflictCheckResult {
   hasConflicts: boolean;
   conflicts: ConflictInfo[];
-  strategy: 'merge' | 'rebase';
+  strategy: "merge" | "rebase";
   canRetry: boolean;
 }
 
 interface ConflictInfo {
   file: string;
-  type: 'content' | 'delete' | 'add';
+  type: "content" | "delete" | "add";
   ours?: string;
   theirs?: string;
 }
 
 class ConflictDetectionError extends Error {
-  constructor(
-    message: string,
-    operation: string,
-    cause?: Error
-  )
+  constructor(message: string, operation: string, cause?: Error);
 }
 ```
 
 ## Implementation Details
 
 ### Git Commands
+
 - `git fetch origin branch` - Fetch latest
 - `git merge --no-commit --no-ff origin/branch` - Test merge
 - `git merge --abort` - Abort test merge
@@ -152,6 +159,7 @@ class ConflictDetectionError extends Error {
 - `git diff --name-only --diff-filter=U` - List conflicted files
 
 ### Conflict Detection Logic
+
 1. Save current state
 2. Fetch remote
 3. Attempt merge/rebase (no commit)
@@ -163,22 +171,26 @@ class ConflictDetectionError extends Error {
 ## Notes
 
 ### Design Decisions
+
 - Use `--no-commit` flag to test merge without committing
 - Support both merge and rebase strategies
 - Provide detailed conflict information for agent retry
 - Clean up after detection (abort merge/rebase)
 
 ### Error Handling
+
 - GitOperationError for git command failures
 - ConflictDetectionError for detection-specific issues
 - Return structured errors for agent consumption
 
 ### Dependencies
+
 - simple-git library (already used in GitOperationsService)
 - NestJS @Injectable decorator
 - Logger for debugging
 
 ## Next Steps
+
 1. Start with TDD: Write failing tests first
 2. Implement minimal code to pass tests
 3. Refactor for clarity