feat(#71): implement graph data API

Implemented three new API endpoints for knowledge graph visualization:

1. GET /api/knowledge/graph - Full knowledge graph
   - Returns all entries and links with optional filtering
   - Supports filtering by tags, status, and node count limit
   - Includes orphan detection (entries with no links)

2. GET /api/knowledge/graph/stats - Graph statistics
   - Total entries and links counts
   - Orphan entries detection
   - Average links per entry
   - Top 10 most connected entries
   - Tag distribution across entries

3. GET /api/knowledge/graph/:slug - Entry-centered subgraph
   - Returns graph centered on specific entry
   - Supports depth parameter (1-5) for traversal distance
   - Includes all connected nodes up to specified depth

New Files:
- apps/api/src/knowledge/graph.controller.ts
- apps/api/src/knowledge/graph.controller.spec.ts

Modified Files:
- apps/api/src/knowledge/dto/graph-query.dto.ts (added GraphFilterDto)
- apps/api/src/knowledge/entities/graph.entity.ts (extended with new types)
- apps/api/src/knowledge/services/graph.service.ts (added new methods)
- apps/api/src/knowledge/services/graph.service.spec.ts (added tests)
- apps/api/src/knowledge/knowledge.module.ts (registered controller)
- apps/api/src/knowledge/dto/index.ts (exported new DTOs)
- docs/scratchpads/71-graph-data-api.md (implementation notes)

Test Coverage: 21 tests (all passing)
- 14 service tests including orphan detection, filtering, statistics
- 7 controller tests for all three endpoints

Follows TDD principles with tests written before implementation.
All code quality gates passed (lint, typecheck, tests).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/scratchpads/orch-109-lifecycle.md

@@ -0,0 +1,113 @@
+# Issue ORCH-109: Agent lifecycle management
+
+## Objective
+Implement agent lifecycle management service to manage state transitions through the agent lifecycle (spawning → running → completed/failed/killed).
+
+## Approach
+Following TDD principles:
+1. Write failing tests first for all state transition scenarios
+2. Implement minimal code to make tests pass
+3. Refactor while keeping tests green
+
+The service will:
+- Enforce valid state transitions using state machine
+- Persist agent state changes to Valkey
+- Emit pub/sub events on state changes
+- Track agent metadata (startedAt, completedAt, error)
+- Integrate with ValkeyService and AgentSpawnerService
+
+## Acceptance Criteria
+- [x] `src/spawner/agent-lifecycle.service.ts` implemented
+- [x] State transitions: spawning → running → completed/failed/killed
+- [x] State persisted in Valkey
+- [x] Events emitted on state changes (pub/sub)
+- [x] Agent metadata tracked (startedAt, completedAt, error)
+- [x] State machine enforces valid transitions only
+- [x] Comprehensive unit tests with ≥85% coverage
+- [x] Tests follow TDD (written first)
+
+## Implementation Details
+
+### State Machine
+Valid transitions (from `state.types.ts`):
+- `spawning` → `running`, `failed`, `killed`
+- `running` → `completed`, `failed`, `killed`
+- `completed` → (terminal state)
+- `failed` → (terminal state)
+- `killed` → (terminal state)
+
+### Key Methods
+1. `transitionToRunning(agentId)` - Move agent from spawning to running
+2. `transitionToCompleted(agentId)` - Mark agent as completed
+3. `transitionToFailed(agentId, error)` - Mark agent as failed with error
+4. `transitionToKilled(agentId)` - Mark agent as killed
+5. `getAgentLifecycleState(agentId)` - Get current lifecycle state
+
+### Events Emitted
+- `agent.running` - When transitioning to running
+- `agent.completed` - When transitioning to completed
+- `agent.failed` - When transitioning to failed
+- `agent.killed` - When transitioning to killed
+
+## Progress
+- [x] Read issue requirements
+- [x] Create scratchpad
+- [x] Write unit tests (TDD - RED phase)
+- [x] Implement service (TDD - GREEN phase)
+- [x] Refactor and add edge case tests
+- [x] Verify test coverage = 100%
+- [x] Add service to module exports
+- [x] Verify build passes
+- [x] Create Gitea issue
+- [x] Close Gitea issue with completion notes
+
+## Testing
+Test coverage: **100%** (28 tests)
+
+Coverage areas:
+- Valid state transitions (spawning→running→completed)
+- Valid state transitions (spawning→failed, running→failed)
+- Valid state transitions (spawning→killed, running→killed)
+- Invalid state transitions (should throw errors)
+- Event emission on state changes
+- State persistence in Valkey
+- Metadata tracking (timestamps, errors)
+- Conditional timestamp setting (startedAt, completedAt)
+- Agent not found error handling
+- List operations
+
+## Notes
+- State transition validation logic already exists in `state.types.ts`
+- ValkeyService provides state persistence and pub/sub
+- AgentSpawnerService manages agent sessions in memory
+- This service bridges the two by managing lifecycle + persistence
+
+## Completion Summary
+
+Successfully implemented ORCH-109 following TDD principles:
+
+### Files Created
+1. `/home/localadmin/src/mosaic-stack/apps/orchestrator/src/spawner/agent-lifecycle.service.ts` - Main service implementation
+2. `/home/localadmin/src/mosaic-stack/apps/orchestrator/src/spawner/agent-lifecycle.service.spec.ts` - Comprehensive tests (28 tests, 100% coverage)
+
+### Files Modified
+1. `/home/localadmin/src/mosaic-stack/apps/orchestrator/src/spawner/spawner.module.ts` - Added service to module
+2. `/home/localadmin/src/mosaic-stack/apps/orchestrator/src/spawner/index.ts` - Exported service
+
+### Key Features Implemented
+- State transition enforcement via state machine
+- State persistence in Valkey
+- Pub/sub event emission on state changes
+- Metadata tracking (startedAt, completedAt, error)
+- Comprehensive error handling
+- 100% test coverage (28 tests)
+
+### Gitea Issue
+- Created: #244
+- Status: Closed
+- URL: https://git.mosaicstack.dev/mosaic/stack/issues/244
+
+### Next Steps
+This service is now ready for integration with:
+- ORCH-117: Killswitch implementation (depends on this)
+- ORCH-127: E2E test for concurrent agents (depends on this)