Update Python version requirements and fix compatibility issues

- Bump minimum Python version from 3.11 to 3.13 across all apps
- Add Python 3.11-3.13 test matrix to CLI workflow
- Document Python 3.11+ requirement in .env.example
- Fix Starlette Broadcast removal with in-process fallback implementation
- Add _InProcessBroadcast class for tests when Starlette Broadcast is unavailable
- Refactor API key validators to read live settings instead of cached values
- Update database models with explicit

packages/py/aitbc-agent-sdk/aitbc_agent/__init__.py

@@ -0,0 +1,18 @@
+"""
+AITBC Agent SDK - Python SDK for AI agents to participate in the AITBC network
+"""
+
+from .agent import Agent
+from .compute_provider import ComputeProvider
+from .compute_consumer import ComputeConsumer
+from .platform_builder import PlatformBuilder
+from .swarm_coordinator import SwarmCoordinator
+
+__version__ = "1.0.0"
+__all__ = [
+    "Agent",
+    "ComputeProvider", 
+    "ComputeConsumer",
+    "PlatformBuilder",
+    "SwarmCoordinator"
+]