Fix Streaming, Memory, SQLAlchemy Cleanup and Reliability Issues Acro…

[harshdesaii]

Description

This PR resolves low severity issues related to streaming correctness, memory consistency, configuration validation, SQLAlchemy design, and improves overall code quality.

Fixes # (issue)

• Replaced fake streaming in HuggingFace model with true token-level streaming using TextIteratorStreamer
• Fixed async-safe streaming execution without blocking the event loop
• Fixed mutation of caller-provided kwargs in OpenAI model
• Fixed chat_stream() to persist full streamed responses into memory
• Implemented missing abstract methods in EntityMemory(add_message, get_messages, save, load)
• Improved SQLAlchemy memory with proper use of a dynamic table model and removal of static model conflicts.
• Replaced naive hallucination detection with score-based heuristic approach
• Replaced non-deterministic and non-cryptographic hash() usage with sha256 for Integrity checks and Fingerprinting
• Replaced print() and emoji outputs with structured logging
• Fixed retry state leakage in router fallback logic