feat: add A2I generations service and router for handling generation requests

fix: improve MongoDB connection handling and logging in lifespan management

feat: enhance generation parameter handling and update related collections in services

KKP-565 | feat: implement credit pool feature with team management

KKP-524 | feat: implement brand, campaign, and moodboard deletions and audit logiing

KKP-398 | feat: implement AI-powered task list generation and tasklist management

feat: add generation_id to credit transaction models and update service methods

feat: add model service and API endpoints for model retrieval and credit estimation

feat: repo init