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/services/exploitation-checker.ts

@@ -17,9 +17,9 @@ import {
   validateQueueSafe,
   type VulnType,
   type ExploitationDecision,
-} from '../queue-validation.js';
+} from './queue-validation.js';
 import { isOk } from '../types/result.js';
-import type { ActivityLogger } from '../temporal/activity-logger.js';
+import type { ActivityLogger } from '../types/activity-logger.js';
 
 /**
  * Service for checking exploitation queue decisions.