GSoC 2025 Backend Revamp

[rahulharpal1603]

Fixes:
#467
#468
#469
#470
#471

Fixes by @rohan-pandeyy:
#474
#472

I implemented all the changes mentioned in this doc: https://docs.google.com/document/d/1CRnPiuXxg-xtmtSdWu91Ltoc4VwgZoC_iKp0utrGSfg/edit?tab=t.0

Backend is better than ever 😄

Summary by CodeRabbit

Summary by CodeRabbit

• New Features

  • Added user preferences management with get and update endpoints.
  • Introduced folder management and AI tagging endpoints for adding, deleting, syncing, and controlling AI tagging on folders.
  • Added face cluster management API for renaming clusters and retrieving cluster metadata.
  • Implemented image processing utilities for validation, thumbnail generation, classification, and face detection.
  • Introduced singleton classes for FaceDetector, FaceNet, ObjectClassifier, and YOLO with enhanced resource management.
  • Added new database tables and batch operations for images, folders, faces, face clusters, metadata, and YOLO class mappings.
  • Added utilities for face clustering synchronization and recursive folder tree insertion.

• Improvements

  • Enhanced database schemas and APIs with richer metadata, batch operations, and consistent naming.
  • Upgraded object detection models to YOLOv11 with user preference-based model selection.
  • Improved documentation formatting and technical stack accuracy.
  • Renamed and prefixed utility functions for clarity and consistency.
  • Streamlined FastAPI app initialization with lifespan management and executor lifecycle handling.
  • Improved error handling and validation in folder and face cluster APIs.

• Bug Fixes

  • Corrected technical stack version and contribution instructions formatting in documentation.

• Removals

  • Removed album and image management endpoints and associated routes.
  • Deleted legacy face clustering, face detection, NER modules, schedulers, and utility wrappers.
  • Removed background scheduler and related test files.
  • Deprecated database tables and functions related to image ID mapping and albums were removed.
  • Removed thumbnail generation utilities and path-ID mapping helpers.

• Refactor

  • Consolidated and refactored database and utility modules for maintainability and performance.
  • Standardized type annotations and naming conventions across modules.
  • Reorganized configuration constants for model paths and thumbnail directories.
  • Simplified database initialization with consolidated creation functions.

• Style

  • Decreased maximum line length to 300 characters for code formatting.