refactor: move server-agent to agents directory

- Create src/agents/ directory for agent modules
- Move server-agent.ts to new location
- Update import paths in all dependent files:
  - openai-service.ts
  - tools/server-tool.ts
  - routes/handlers/message-handler.ts
  - routes/api/chat.ts

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

src/openai-service.ts

@@ -6,7 +6,7 @@ import { createLogger } from './utils/logger';
 import { metrics } from './utils/metrics';
 import { getOpenAIUrl } from './utils/api-urls';
 import { ERROR_MESSAGES } from './constants/messages';
-import { getServerSession, processServerConsultation } from './server-agent';
+import { getServerSession, processServerConsultation } from './agents/server-agent';
 import { getTroubleshootSession, processTroubleshoot } from './troubleshoot-agent';
 import { sendMessage } from './telegram';