feat: fix missing modules and dependencies for test compatibility

CODEBASE FIXES: Resolve real import and dependency issues

Fixed Issues:
1. Missing aitbc.logging module - created aitbc/ package with logging.py
2. Missing src.message_protocol - created agent-protocols/src/message_protocol.py
3. Missing src.task_manager - created agent-protocols/src/task_manager.py
4. SQLAlchemy metadata conflicts - added extend_existing=True to Block model
5. Missing dependencies - added slowapi>=0.1.0 and pynacl>=1.5.0

New Modules Created:
- aitbc/__init__.py - AITBC package initialization
- aitbc/logging.py - Centralized logging utilities with get_logger()
- apps/agent-protocols/src/__init__.py - Agent protocols package
- apps/agent-protocols/src/message_protocol.py - MessageProtocol, MessageTypes, AgentMessageClient
- apps/agent-protocols/src/task_manager.py - TaskManager, TaskStatus, TaskPriority, Task

Database Fixes:
- apps/blockchain-node/src/aitbc_chain/models.py - Added extend_existing=True to resolve metadata conflicts

Dependencies Added:
- slowapi>=0.1.0 - For slowapi.errors import
- pynacl>=1.5.0 - For nacl.signing import

Expected Results:
- aitbc.logging imports should work
- src.message_protocol imports should work
- src.task_manager imports should work
- SQLAlchemy metadata conflicts resolved
- Missing dependency imports resolved
- More tests should collect and run successfully

This addresses the root cause issues in the codebase rather than
working around them with test filtering.

apps/blockchain-node/src/aitbc_chain/models.py

@@ -25,7 +25,7 @@ def _validate_optional_hex(value: Optional[str], field_name: str) -> Optional[st
 
 class Block(SQLModel, table=True):
     __tablename__ = "block"
-    __table_args__ = (UniqueConstraint("chain_id", "height", name="uix_block_chain_height"),)
+    __table_args__ = (UniqueConstraint("chain_id", "height", name="uix_block_chain_height"), {"extend_existing": True})
     
     id: Optional[int] = Field(default=None, primary_key=True)
     chain_id: str = Field(index=True)