feat(media): introduce MediaRouter and stubs for image and speech generation

feat: Update model references to MiniCPM5 and adjust related documentation and tests for transformers 5.x compatibility

Refactor local provider to support on-device loading with accelerate

feat: Add use_cache parameter to support KV cache handling in models and update tests

Refactor local model configurations and update tests

feat: Update model routing and local provider to support multi-sponsor tiers and auto-class resolution

feat: Ensure full materialization of model weights to prevent meta tensor issues in ZeroGPU

fix: Ensure proper unpacking of BatchEncoding in model generation to prevent AttributeError

feat: Replace llama.cpp backend with in-process transformers backend for local GPU inference

Implement local in-process inference backend for transformers models