refactor: consolidate file layout and break circular dependencies

- Move error-handling, git-manager, prompt-manager, queue-validation, and reporting into src/services/
- Delete src/constants.ts — relocate AGENT_VALIDATORS and MCP_AGENT_MAPPING into session-manager.ts alongside agent definitions
- Delete src/utils/output-formatter.ts — absorb filterJsonToolCalls and getAgentPrefix into ai/output-formatters.ts
- Extract ActivityLogger interface into src/types/activity-logger.ts to break temporal/ → services circular dependency
- Consolidate VulnType, ExploitationDecision into types/agents.ts and SessionMetadata into types/audit.ts
- Remove dead timingResults/costResults globals from utils/metrics.ts and all consumers

src/temporal/shared.ts

@@ -1,6 +1,5 @@
 import { defineQuery } from '@temporalio/workflow';
 
-// Re-export AgentMetrics from central types location
 export type { AgentMetrics } from '../types/metrics.js';
 import type { AgentMetrics } from '../types/metrics.js';